P.M.
As sad as it seems, some grandparents never do really connect with their grandkids. I know women in my age group (60-ish) who couldn't be kept away by herds of wild horses. And others who would need a few wild horses to drag them over to their grandchildren's houses.
If she's not physically or emotionally well, visits or even driving may seem like too much effort, and if the child is too young, rambuctious or otherwise challenging, she may not find visits rewarding enough. That's just the way some people are put together.
Your daughter is likely to "care" to the same extent you do. Unless you fuss about your mother's attitudes, your little girl will probably simply think of your mother as a more distant relative. It happens, and unless there's a lot of family tension, it probably won't be a big deal to her. Let her focus on and enjoy the more available grandparents.