Can I get my mother registered for Medicaid while she is in a coma or persistent vegetative state (don't have POA and not a guardian)?

You cannot be made POA by anyone. Only mom can grant it. The only option may be for the hospital or you to file with the court for emergency guardianship. Get with the hospital social worker.

Get your planning documents in order people!

Does she get bank statements? Do you have access to her home and papers? I have POA for my mother but I don't really need it. I have access to her home and all her papers, plus the passwords on her online account and debit cards. Can you (or someone) rummage around her home for paper copies of documents?

She is currently in a hospital. As I read the medicaid form, it says it can be filled out by an "authorized representative" which it says can be a family member. But we don't have access to her banking account so we would just estimate any savings (wouldn't be more than $5k I think).

Is your mom in the hospital, or a Nursing home? Ask the discharge planning office if a hospital or the business office at the nursing home.

I don't have any first-hand knowledge of this, but I know that the folks that handle this stuff are accustomed to dealing with family members, because the elderly person is often too impaired to fill out forms, collect documents, and answer questions needed for the application. I don't see any reason why not having POA would be an issue. Anybody know for sure?