Hmm this is a really sensitive situation. I think I would take a step back and not try to adopt it right away, since you don't know the neighbor or the situation with the dog. Maybe if you started talking to her and getting to know the dog as well, you could get a better feel for the situation. Perhaps she really loves the dog but doesn't have the knowledge or time to take care of it? Which is not right by any means, but perhaps you could offer to help her take care of the dog before insulting her or asking to adopt it? Then again, I've never been in this situation so I can't be sure this is the right thing either. Sorry if I'm no help

Just wanted to give you some feedback.