Wow! I was gone from the board for awhile and came back to find all of these amazing vegetarian recipes! What an awesome thread! I'm definitely trying some of these recipes.
My advice: If you don't feel comfortable asking them what their preferences are, just go vegan. It's a safe bet and trust me, no one will miss the eat, cheese, milk, etc. There are so many fantastic vegan dishes out there right now. Here are some sites that might give you some inspiration:
olivesfordinner.com
https://wickedhealthyfood.com/
https://fatfreevegan.com/
https://www.veganricha.com/
http://www.isachandra.com/
http://ohsheglows.com/
I have more, but that will keep you busy for awhile.
Have fun cooking for your new neighbors and friends!
~ C