There is a lot of information and resources that are available to you. Below are some questions that may help you to understand what you may need to know.

How can I be authorized to make decisions for my loved one?

There are a number of ways to be able to do this. Below is information that may help you to understand what is available to you to manage your loved one’s affairs when they are in a disorder of consciousness.

Advanced Directives
An advance directive is a document where a person determines what their wishes are for making health care decisions if they become unable to make those decisions on their own. Your loved one may or may not have this document, but it is important to know if there is such a document. Sometimes this is available in their health care record.

Below is a website that gives you more understanding of what this document includes.
Advance Directives: A Family Caregiver's Guide
From UHF Next Step in Care

Health Care Proxy
A health care proxy is a person designated to make decisions for a person who is unable to do so. It is a legal document where your loved one appointed a person to make those healthcare decisions for them if they are unable to make them themselves. You may want to check if your loved one has such a document.

Below is a website that will help you better understand what this is.
Health Care Proxies
From Medicare Interactive

Durable Power of Attorney
A durable power of attorney is a person who has been designated by your loved one to make either health care or financial decisions if they are not able. It is a legal document that had to be completed prior to their inability to make decisions. You may want to see if there is such a document that your loved one has signed. 

This website gives you more information on what is a POA and how it may help you.
What Is a Power of Attorney (POA)?
From AARP

What if my loved one does not have any of the above documents?

Obtaining Legal Guardianship
Many times, your loved one may not have any legal documents in place, and you will need to obtain guardianship in order to deal with finances and health care decisions. A legal guardian is a person who can be appointed by a court to make these decisions. There are ways to get emergency, temporary, or permanent guardianship. Initially, you may want to look at emergency/ temporary guardianship as it lasts for only 90 days depending on your state laws and then go from there as needed.

Below is a link to understanding temporary guardianship.
Temporary Guardianship | What It Is, Why It's Needed & More
From Superior Notary Services

Below is a website that has a fact sheet about permanent guardianship and why it may be necessary.
Understanding Adult Guardianship
From Caring.com

What if I do not want to be the person’s guardian?

This can be somewhat overwhelming, and another person can be appointed to be a person’s guardian. Below is information about this.

Public Guardianship Office (PGO)
From Georgia Department of Human Services Division of Aging Services

Doctors are talking about decisions that I need to make about “do not resuscitate (DNR)” and “withdrawal of care.” What does this mean?

Sometimes a person's injury is so severe that your doctor may start asking you questions about what your loved one’s wishes were regarding how they want to live. You may hear words like, “do not resuscitate (DNR),” “withdrawing or withholding care,” or “brain dead.”

It is important to understand and think about directives like “do not resuscitate” before making any decisions. Since making these decisions can be extremely difficult, especially since it is not often clear if your loved one will recover, you may want to review the section on “Will my loved one regain consciousness?” to help you better understand prognoses for people with DoC.

What is DNR (do not resuscitate)?

A DNR means that a person has decided not to have cardiopulmonary resuscitation (CPR) attempted on them if their heart or breathing stops. Sometimes a family has to decide for their loved one. DNR orders are written by a physician after a discussion with you as a family member about the severity of your loved one’s medical condition and what the wishes of your loved one would be if they stopped breathing. DNR orders guide your healthcare providers during an emergency when there is typically no time to discuss what to do.

What does withdrawal or withholding care mean?  

This information is for people who may be considering withdrawing care of their loved one, a term, which broadly speaking, is used by healthcare personnel to refer to the discontinuation of life-prolonging treatments such as a ventilator, dialysis, vasopressor medications, extracorporeal bypass, artificial nutrition, and others.
 
These are discussions you and your doctor will have when death may be inevitable or your loved one is terminal despite continued treatment. The definitions of how this is determined may vary from state to state.

Below is a more detailed description of DNR and withdrawal of treatment.  
End of Life: Options for Care and Choice (PDF)
From Compassion and Choices

What is a DNR order? and What is Life-Sustaining Treatment? (PDF)
From Shepherd Center

If we choose to withdraw or withhold care what are options for care?

Hospice Care or Palliative Care Programs
You may hear about these types of care from your doctors as options for your loved one, and your social worker or case manager can help you to better understand these options. Sometimes, representatives from the Palliative or Hospice Care departments can visit you to provide more details and guidance. You will not have to do this on your own. Palliative or Hospice Care can be provided in the hospital, in a specialized program, or at home, and a team of clinicians provides this care, offering medical, psychological, and spiritual support.

To better understand the differences between palliative and hospice care, the website below will describe the differences.
Types of Care: Palliative, Comfort, Hospice, Bereavement
From CaringInfo

This website helps to understand what kind of treatment options are available.
End of Life: Options for Care and Choice
From Compassion and Choices

Losing a loved one is very hard and there can be support for you as well. Below is a website that explains this type of care.
What is Bereavement Care and How to Find Services
From CaringInfo

Hospice Foundation Of America is a great resource to talk with people about hospice.
(800) 854-3402

What does brain dead mean?

Brain death is a clinical and legal definition of death and is defined as the irreversible cessation of all brain activity. And although brain dead, a person’s heart may still be beating, their chest may still rise and fall from the ventilator, and their skin may still be warm. While thinking of these descriptions and directives, you may want to look at the "What Assessment Tools Will Be Used to Determine My Loved One’s Level of Consciousness?" section in the Overview of Disorders of Consciousness - Body and Mind.

These articles from Verywell Health have more information:

What It Means to Be Declared Brain Dead

Confirmatory Tests for Brain Death