I think you've given gram some good advice, Cedars.
Just wanted to add a couple of comments. KS, you suggest gram should have read a particular book before raising her daughter since she is in a cult. I wish it was that simple. AS parents we cannot control how our children turn out, unfortunately, no matter how many books we read! We also make many mistakes in raising our children. I did, because I raised them in the cult.
Giordano's observation about the gram/daughter relationship got me thinking. My eldest daughter and I have a sometimes difficult relationship. Of my girls, she is the one most likely to return to JW land, although with my mom (her gram) gone that danger may be lessened. Her grandmother had a major influence on her, unfortunately. So it can go both ways. I should add that my other daughters are all open-minded critical thinkers who will never go back. It's just my eldest who is a black/white thinker attracted to cults.
However, she is allowing my granddaughter to attend children's sessions at an evangelical Christian group with some family friends. My granddaughter is always telling me stuff about God, heaven, etc. I try to give her different perspectives, tell her I don't believe certain things and that there are many different religions. We have some great discussions (she's 7). I respect her mother's right to raise her and teach her what she will, whether I agree with it or not. I also have worked really hard to not interfere because of my own experience with my mother. I'm simply trying to encourage critical thinking and let my granddaughter know that there are other valid viewpoints (a la Dawkins).
However, my granddaughter recently told me that her mom doesn't want her at my house because of these conversations. So sometimes you just can't win for trying. It really is a very complex thing when you are a grandparent who wants to do right by your grandchild.
Now, I should add that if my daughter does ever start attending JW meetings, I may find it much harder to be tolerant. I don't think it's simply "moral panic". The danger to this 3-year-old is very real and gramma is right to be worried.
PS - never underestimate the intelligence and reasoning capabilities of a 3-year-old.