Butter shouldn't be given to people who are lactose intolerant. Lactose is in anything milk-related. Intolerance will not kill you, so perhaps your DD has decided to put up with the effects. I would rather be well, personally.
If you have invited people to lunch, shouldn't you expect to give them something they can eat? If you have someone who cannot digest certain foods (which is what food intolerance means), it's probably better to ask them what they can have. They may well suggest bringing something with them. Those lactose intolerant can often eat vegan puddings as they don't use milk (animal product), but you would have to check the other ingredients. If it has a base you may be running into wheat/gluten problems. In the case of the quiche suggested by the OP for her guests sounds ok for their needs but would not be ok for anyone with gluten/wheat or lactose problems. You could make one crustless tart, but those lactose-intolerant guests would still be unable to eat it. Onions are my "most likely to send me to sleep while driving home" foods because of the very hight level of the "wrong" sort of sugars in them. I wouldn't eat them, although I would look longingly in their direction.
Somebody suggested strawberries, I think. It wouldn't solve your problems with me, I'm afraid, but a small portion of raspberries and some lactose-free (probably vegan) ice cream would.
You may think this is difficult for one day, and I do appreciate the OP's guests have all chosen their way of eating and will neither die nor be ill if something creeps in. But those of us who don't have a choice a) like being as well as possible as often as possible and b) probably won't come unless they know you very, very well because we know what a pain we are 
Terrible relationship with DIL - am I the problem?
difficult relationship with son




