Have you talked with her about this directly? As in "I miss seeing you alone, without your family interrupting?" My guess is that this has more to do with her than them -- she is letting them know where she is, answering the phone, etc.

I have (had) a friend who started to do the same thing. She often babysat for her daughter. It was a strange situation, where the daughter's husband had some problems and so the daughter did not trust him to watch his own children. My friend's daughter always had some crisis or another and my friend would be subsumed by it. The last time I had plans to meet her (at a bar), she agreed to babysit at the last minute and wanted to bring a six year old.

So, on the one hand, my friend was being taken advantage of by her daughter--- but on the other, she was letting it happen. For my friend, it was easier to ask me to focus my activities around her grandkid than it was for her to tell her daughter 'no.' She would complain about the situation, but felt like there was nothing she could do.

I am not sure if the situation with my friend is anything like the situation with your friend. For my friend, I think it was more of a martyr streak than her family being jealous.

It could be just because it is summer, too -- the kids are out of school. Maybe in the fall your friend will be back to her normal pattern.