How to deal with an elderly parent who refuses to go to rehab but physically cannot get out of bed?

An elder with dementia cannot really thrive in rehab to begin with, so..........they can't follow directions, they can't remember to do the exercises, they can't follow cues very well, it's just too much for them to process all the requirements that go along with rehab. Who's suggesting rehab for a bedbound dementia patient???

You do not give nearly enough details in your title with no body of information, which makes it nearly impossible to give you lucid comments. Come back and elucidate on your situation and let us know:

1. Does your mother live alone in her home?
2. Are you caring for her there?
3. How is she functioning being bed bound?
4. Who's recommending rehab in the first place?

My first inclination is to say it's time for mom to be placed in Skilled Nursing, with all these issues going on. But give us more details first and you'll get better comments/suggestions.

Assuming this is the mother you describe in your profile and there’s a dementia diagnosis, I’d consult her doctor on a plan. Make it clear that she’s unable to care for herself, cannot get out of bed, won’t cooperate, and has no help. Refuse to accept being cast into the role or to accept that rehab won’t happen. Maybe it’s time for care beyond rehab. A hospital social worker may also be of help. If all else fails report her to APS as a vulnerable adult

You need to do two things, ask them what they want and be clear about what you are prepared to do. If they state they want you to care for them but you are unable, they need to either go to rehab or find a different solution. I

Ask her what she wants to do about her situation.