The matter you outline here is tremendously complicated. Best to discuss with an attorney, where you can go over the details in private.
We do not have a client/attorney relationship until you make an appointment, we discuss your case face to face, I accept a retainer, and we explictly agree to enter into representation.
These issues require a knowledgeable social worker familiar with government programs. Generally, a person would not lose Social Security when they are in a rehab facility. However, there may be housing programs where the Social Security is used to pay for the program. Find a non-profit that helps disabled and see if you can work out the social services issues and options.
You should find an attorney in your area who specializes in elder law. He or she would be familiar with issues surrounding disabled people and their benefits and POAs.
"Patient Dumping" is prohibited by a federal statute called EMTALA, and you should ask potential attorneys about that too.
Look under the "Find a Lawyer" tab here on Avvo - you can sort by town and specialty. Good luck.
DISCLAIMER: Any information contained herein is intended for general informational purposes only. The information should not be construed as legal advice and does not create an attorney-client relationship. Any response given does not result in any further obligation to provide an additional response. Seek competent legal counsel for advice on any legal matter.