I agree with Zette and others here–I think the death of the grandmother made this woman babble a lot more than she usually would ordinarily. However, if she’s talking about stuff that you have no interest in (slews of kids) then by all means, run. You might be doing her a favor anyway–why does she need to waste time with someone who is weirded out by her and doesn’t apparently want the same things that she wants?
It’s not a huge deal–if you don’t want to write her back, you shouldn’t. But I strongly suspect that if you’d written to her a few months ago or a few months from now, her response probably wouldn’t have seemed so “off.” A death in the family can really throw you for a loop.