Advantage and Frontline are much less dangerous to you and your (her) pet than the over-the-counter medications from Hertz and others. However, there's no reason for you to increase your exposure to the product. If she does use it, she should do ASAP so it's on there and dry before the dog arrives at your house.
Only you'll be able to make the judgment call on the liklihood of your house getting infested and YOU needing to have your animals treated. If there's high liklihood of that, then it makes more sense to have her treat her dog - your exposure will be less.
Before those treatments were available, I tried everything including garlic, flea collars, bathing, combing, vaseline, yard treatments, house treatments, vacuuming with and without treatments, washing, etc. And I still had fleas on my pets and in my house. Since the treatment, if I get fleas, I treat once, clear out the house and never have to do anything again - unless I adopt a new animal with fleas. Although there is a serious, small risk of harming the animal, I have chosen to risk it based on the long term benefit. So that's my bias - now you know.