I have a GMC van I bought a year ago, which I am happy with because I don't live "in" it, I live "out" of it. Most van people say something similar. It is very much an outdoor living style. With a smallish Class-C (24' or so) or a travel trailer 20' long, you can live in it. IOW, not be outdoors all the time. When I've been in places with a lot of regular RVs, those people spend most of their time indoors.
I suspect your friend coming from a lifetime of S&B will want something she can "live" in. Unfortunately, when I was looking at Class-Cs a year ago, rigs that were already 20-years old were selling in the $20,000 and up range. I didn't want something so old, as I figured there are likely to be maintenance problems of all sort with the RV stuff, especially plumbing, even if the engine has low-mileage in it.
Your friend does not sound like someone who can deal with possible continuing maintenance problems, especially if she has some sort of disability, so I think she should be prepared to spend more money and buy something newer. You might check some of the videos,
https://www.youtube.com/results?search_query=buying+an+older+rv