I am 54 and just started to have the same symptoms. I had spent the last 3 or 4 months on the couch as just walking from the bed to the couch was a painful, stiff hipped journey that seemed to take more and more out of me.
I began to research the combination of meds they had me on and anything else that had changed in the last year. I was soooooo lucky. It turned out the doctor had prescribed Welbutrin for me which is known to cause drug induced arthritic symptoms. So I stopped that and forced (and I do mean forced) myself to do 20 minutes of stretching every morning because the less you do, the less you can do.
I am feeling better, some days are way more stiff than others, especially when it is damp and/or raining outside.
I am sure it was the Welbutrin that kicked everything off because I have tried several times to take a capsule and every time I do, I have an immediate increase in symptoms, pain, and swelling.
Be gentle with your Mom. She has to make her own decisions. If she isn't ready to address the problems and you can't talk her into working to find solutions, then you have done all you can. Respect her choices for it is her pain.
"Always remember thirty is old to a teenage, but sixty is a baby to the eighties."