She loves her grandchildren but does not provide any daycare for them and has no desire to take them out for days or spend prolonged periods of time with children that aren't her own
The thing is, families have shrunk. So, if your grandparents don't take you out for an ice-cream or spend a couple of hours pottering round the zoo (with parents along too), there isn't necessarily an extended family of aunts, cousins, uncles and so on to connect with.
All the research shows that the more connections people have, and feeling like their lives matter, makes them healthier and happier. Kind of obvious really. Also, having other not-parents but adults around while children are in the teenage years is also a really good when they don't want to listen to the parents.
My mum will be living with me in old age, she's been an exemplary mum to me, and that will be the least I can do, unless she has care needs like dementia. My dad shows sporadic interest in me, and at times very little in my children, and I think a home would be better.