It’s not necessarily what I would choose, but my mom had the same problem and after a lot of research decided on OpenBSD, plus classic X utilities (xv, xpdf, gvim, xterm, etc). It’s something of a learning curve, but they all change very slowly and are big on backwards compatibility, so once you figure out how things work and get them set up for your needs it’ll probably keep working that way for a long time to come.
