Aunt's nursing home hinders exit

My aunt is in a nursing home. They tell us she isn't allowed to leave unless she gets the doctor's permission. If she does, she has to sign a statement saying she doesn't hold them liable and will lose all her healthcare coverage. She is on Medicare. Can you help?
No doctor or any other healthcare provider has the authority to strip you of your health insurance benefits, including Medicare. There are requirements that must be met in order for Medicare to cover some of the cost of your aunt's current stay in the skilled nursing facility, or SNF. However, it's unlikely that the care she's already received from the home would be denied because she left against the doctor's orders. What determines coverage is that there was a qualifying three-day hospital stay before entering the SNF, that your aunt has Medicare Part A with days left in the benefit period and that the services she received in the SNF were ordered by her doctor and are related to the treatment of her diagnosed condition. For more information about benefits, visit the Medicare Rights Center at medicareinteractive.org.

Source:Los Angeles Times