I know my osteopath specialised in stroke patients. Whether you’d get the ageist reception, I don’t. I do suspect a good one would have got some movement to your mums stroke side. With some of the muscle work and manipulation, it can be weeks before you notice any real result. I think that’s why so many give up, aside from the cost, they’re looking for instant improvement and feel its a waste of money. Don’t get me wrong, some improvements can be instant but that depends on the nature of the issue.
But it can be as costly as a private physio and how much good they could do for your mum is anyone’s guess. I know there are plenty of videos on the net of the kind of things they do. There is one Scottish guy who teaches it whom I find fascinating to watch, I watched him Tiktok but I can’t find him youtube. And actually, we were talking about this in another post:
You live down south don’t you? You might have better luck than I did finding a teaching college, as they all seem to be down that way.
The difference between an Osteopath and a Chiropractor
And I’m just going to throw this one in that I’ve just come across just because I do these and my back feels so good afterwards 
Lorraine