How come she "can" bring her dogs with her to your house when she visits...???
Do you actually say "yes you can bring your dogs..." or does she ask permission first, or does she just 'assume' she 'can' bring her dogs to your house and you 'let' her????
To me, that is the problem.
The problem of what is not said... to her, and whether she 'can' or cannot bring her dogs.
It is your house, your rules.
And it is her responsibility, to find other plans for her dogs if she cannot bring them to your house. Too.
AND it is your responsibility, to tell her she CANNOT bring her dogs to your house.
And yes, if a person is allergic to an animal, it doesn't matter how big the house is or not... as soon as they come in contact with the animal or are in the vicinity of the animal or are sitting on/in the area an animal was... they will react with their allergy.... it is the dander and fur, that causes allergic reactions in people. And what is in the air. They don't have to actually pet the animal to get an allergenic reaction....
Next, at least you asked permission first, if you can bring your dog to her home. And she responded with, no. But she offered you alternatives. Which is reasonable and thought out.... so she tried to work it out.
But for your house, then just tell her, she cannot bring her dogs to your house in the future... because it is just ruining your home.
all the best,
Susan