You don't sound ignorant, I just thought maybe you were alluding to something. Now that I think about it, it does sound a little fishy that the cops weren't notified. You have to wonder if she was privy to the husband's frame of mind. Perhaps the guy had a bad temper that only came out behind closed doors?
I know it's against TOS to implicate potentially innocent people, but I can honestly envision the mother taking advantage of this and exploiting it to get away from her husband.
That's probably not the case though. The child either conveyed in some fashion that she was molested, or the mother misconstrued it as such, and was possibly shell-shocked enough to flee to her out-of-state family and not call the police. Then again, don't you think the family she went to visit would at the very least encourage her to call the police?