A friend of a friend set up a similar arrangement with her mother. Mother sold off a large house, bought a larger house with her DD and SIL 80 miles away. She has a lounge and an en-suite bedroom, shares a kitchen with DD. The mum loves clutter, which is just as well as she has nowhere for her stuff, to the point that 2 years on most of her things are still in boxes. Daughter is into minimalism and is a clean freak. When DD has friends over, the mum has to stay out of the way. She was very active when she lived in her own place, clubs, friends, keeping fit but there isn’t quite so much for her to do where she is now and doesn’t have the facilities to have friends to stay over. She is effectively a guest in her own home and can not afford to move back to the area she came from.
When this was all being discussed it sounded wonderful to the mum and daughter but the rest of us could see that this would never work. We worry about the time the mum may need help, as the daughter and SIL are not likely to be the ones giving it.
If you want to be close to your daughter buy somewhere nearby but don’t move in together.