In June we had house guests. Since the last time we'd seen them they converted to the paleo diet. (Short version: no grains, no dairy, no legumes, lots of meats, veggies, nuts, and fruits, limited raw honey, dark chocolate.) We had to feed them, while also feeding my older son who won't eat meat unless it's bacon.
Almost as soon as they were gone I had vegetarian friends come over for a play date, and I had to feed them lunch.
And then the next day my mostly vegetarian friend and her utterly carnivorous husband and son came for a visit and I had to feed them, too.
I say "had to feed them" as if it were a trauma, which is wasn't. I like feeding people. I say "had to" because they were in my home over mealtimes so I was required by the laws of hospitality to offer them sustenance. Basic hospitality also required that I provide food that was acceptable to them. Hospitality doesn't say anything about judging their dietary choices. Why they eat what they eat is immaterial. Religious reasons, ethical reasons, and personal health reasons are all the same. I am supposed to make whatever small accommodations are necessary to feed them food that they can eat. Their duty as guests was to eat of the food which I put in front of them and shut up about it. My follow-up job was to notice what they ate without mentioning it, using the information only to prepare the next meal so that there is enough that they can eat.
Now, the laws of hospitality do not require any of the following: that the food be fancy, that the food be homemade, that the food be in violation of my own ethics. You don't have to cook it yourself, you don't have to serve meat if you're a vegetarian, you don't have to serve bacon if you keep Kosher. You simply have to assure that you share of what you have. If you are a vegetarian feeding an omnivore, that may mean you serve a meal that is heavier than you usually eat. If you are an omnivore feeding a vegetarian it means that you cannot mix the bacon into the salad before putting it on the table. You are perfectly free to offer the bacon on the side, just don't use the bacon fork to stir the salad dressing.
Hospitable food can come in many forms: a tray of cheese, grapes and crackers, a take-out menu from a local restaurant, a frozen lasagna, an offer to host a meal out at a restaurant, an offer to host a pot-luck. It can be served on fine china, everyday plates, plastic plates, paper plates, or eaten straight from the take-out box with disposable chopsticks. How you serve your food is determined by the company and the occasion. I don't recommend showing up with a bucket of fried chicken and suggesting everyone sit in front of the coffee table watching TV the first time you meet your future in-laws, but I don't know your future in-laws so maybe it would be perfect.
While my friends were visiting, all of them, the whole mixed, messy, wonderful lot of them, I picked meals that were flexible. It meant I served taco salad twice in one week. Mix up a pile of greens. Cook up some black beans (or open a can). Open some jars of salsa, a tub of sour cream, and a bag of tortilla chips. Shred some cheese. Cook up some ground beef (or turkey) with taco seasoning of some kind. Let your guests serve themselves. If you have a vegan and a paleo at the same table they will both be able to eat together. I'm sorry I don't have any pictures. My photographer was too busy enjoying the company.
ETA: We made it again, so now there's a picture: