If you are making anything from a mix, you will need to carefully read the list of ingredients. Anything with Milk solids, whey, milk, casinate (sp?) all contain milk. If you are sending over salad dressing or using sauce from a jar, check the label. My dh is lactose intolerant and it is hidden in so much. Cheeses are tricky too.
How about a grilled meat, either baked sweet potatoes or regular potatoes. Buying one of the steam fresh veggies with no sauce is good.
I would go bland. For my dh, I know what he can and cannot eat, but I do not expect others to go crazy trying to feed him.
When I was on the receiving end of service like that, I just told others to make it as simple as possible. We have quite a few didfferent spices he can add to his meat to favor it up some.