No, and no, unfortunately. The only thing she might be persuaded to have would be a topper of some sort, but it would have to be quite thin, and washable. I bought her a featherbed topper once and it was instantly rejected - ended up at the tip. That was back in the days when I was 'just pressing ahead'.Can you be sneaky with the mattress replacement - does she ever stay away from home at all? Just don't tell her and switch the mattress while she's away...
I know what you are saying, and I thank you for your understanding and contributions. Mum is a difficult character, with some mental health issues that make life much harder than it ought to be. I (now) know better than to try and force an issue. It's hard sometimes, when I can see solutions to so many of her problems, but if she cannot accept them there is little I can do.