There are many elderly - I mean 80/90s - who have never worked. Those people belong to a generation for whom work outside the home was not always expected or possible (due to bringing up kids etc).
Those in their 70s now were more likely to work, and those of my age group - I'm 60 - are almost certainly to have worked since age 16 and returned to work once children reached a certain age. Many have already retired age 55 if in certain occupations.
I'll be working full-time until 67 BUT I took a long time out with DD. I have a gap in my contributions which I can make up to get my full state pension. I'm not married. I've got a small occupational pension as well, which will be taxed.
I've been credited with NI contributions until DD was age 12. I haven't claimed any other benefits at all, ever, apart from CB.
I work in the charity sector in a low-wage area and frequently come across women whose income is low. They are mainly women with health conditions getting PIP or DLA, in Support Group ESA, in receipt of Housing Benefit and getting s couple of premiums on top.
I find there's a lot of resentment towards these women, some of whom have probably never worked. I have a cousin in this situation. She worked in a flower factory, became allergic to something, and has not worked since. She's 64. She'll get pension credit to top up her income to the state pension amount because she won't have enough contributions in.
It's becoming harder and harder to claim benefits though.
The OP's mother will be moved from DLA to PIP and it's a different benefit so she may no longer qualify. UC is taking over from old-style benefits and is stricter.