I do think that if you know of this sort of thing, you *do* have a responsibility to offer hospitality to your guests. What sort of hospitality are you offering to your mom? None. And she's your MOM.
So when this sort of thing is known, yes, I think etiquette says you need to offer them food that, medically speaking, they can eat. Ethically as well.
I can't imagine you'd think it was okay to have a vegan over to dinner and serve baked beans w/ bacon, mashed potatoes w/ butter and cream, string beans w/ bacon, corn w/ butter, sauteed carrots with butter, salad with anchovies, and lamb. Oh, and break w/ sausage bits in it.