How do I deal with an extremely nosy and inquisitive Mother in Law. She asks a LOT of questions.?

She will often say, "how's your Mom?" And I'll give her the garden variety "Mom is great...really seems to be enjoying her retirement" kind of answer but she'll just keep pressing for more details such as, 'does she date? 'does she do things w/ her grandkids?" "how often do you see her?" She aks questions about EVERYTHING and I want to stangle her. I really can't stand it!