The werewolves will act much like any other intelligent, feral creature would act; they'll try to take out whatever seems like the greatest threat to them first. With that in mind, it's very plausible that they'd go after Mrs. O'Leary first, since she seems like such a large and dangerous threat to them.

That said, it's up to you how far you want to play with that! It is just as possible that without a larger number of the werewolves present, they'll be wary of taking her on as well. It's mostly up to you and whatever will be the most fun for you to play with!