Definitely go back to physio! It is certainly not too late. I'm a physio student from NZ. I can't give professional opinion yet but it is possible that physio might help with both the muscle tone and nerve pain. Plus Sue is right, it will be great for your mum to be around others who she can relate to and have fun with.
I'm sorry that this has happened; I'm a survivor myself. Recovery is an ongoing process and never really stops. (After 15 years I can still see improvement; physically and cognitively) To me activity, and being around others is so important; I would restart the physio; people mean well, so do doctors, but if I had a dime for every time I proved the doctors wrong I'd be a wealthy woman!
Just to add, your mom's lucky to have you.
Sue