At what point is it time to stop trying to give a Parkinson's patient therapy to strengthen their leg muscles?

My mother is 88 years old, has not been able to walk for 2 years now. She had
therapy years ago, but the therapist discontinued because he said she is not making any progress.

She is now in a nursing home and for over a year she has not been able to walk on her own, nor stand on her own. She has had a few falls since in this new nursing home and they have called me about giving her therapy to see if they can strengthen her legs so that they won't have so much difficulty when transfering her.

I told them I believe it's too late to see any type of improvement in her ability to stand or strengthen her legs. Don't you agree that there is a time to stop giving unnecessary treatment to an elderly patient?