I hate to say this, but as much as I love my adult DC, I so much hate them coming for something to eat, because one is a vegetarian who is gluten free (by choice,) and the other is a vegan. I don't eat any red meat, and DH does (not much as it's rarely in the house but he's not too fussed. He does like it occasionally though.)
Doing meals for me and DH is OK/easy, as it's mostly anything but red meat. Occasionally I will do DH a roast beef meal that I buy pre cooked from M & S or Morrisons, or a minced beef pie and chips, or beef pasty and mash and veg, and have a chicken pie myself or roast chicken meal when he has the beef one. But 95% of the time we eat the same. White meat or fish with vegetables or pasta or pizza or spag bol with quorn mince or cod and chips, or a big chicken and veg stew, or salmon and boiled potatoes and veg (or a massive salad, etc.) Or even beans on toast!
But with DC who are a gluten free vegetarian and a vegan - and their partners are one meat eater (but hates lamb and pork,) and one vegetarian, (so FOUR types of food preferences,) then and me and DH with ours, it's a clucking nightmare. So when they all come round, I just order takeout to be honest. When you factor in all the different types of food, and preferences, and chopping, peeling, and baking, and cooking for 6 people with differing food tastes, and the time it takes, and all the gas and electricity used, it doesn't cost much more for a takeout for 6.
I have catered for all 4 of them - 2 DC and their partners a number of times before, like maybe a dozen or so, but tbh it got to be such a pain in the arse, and so much hard work, and stress, that I just stopped. Getting takeout is so much easier, and as I said, not any more expensive. Plus, I can count on the fingers on one hand, the amount of times they have cooked for us. In ten years!
But yeah tl;dr, I won't cater for people who won't eat/don't eat pretty much the same as us. I did when the DC lived at home (their vegetarian/veganism started 3-4 years before they left for uni, and continued on while they were there, so I did it for 7-8 years,) but I won't do it now. Seriously CBA.
Seriously, the old internet meme still holds up so well. 'When I was a child, you had 2 choices at mealtimes. EAT, or STARVE.'