Do they keep a kosher home? If so, would call The Butcherie in Brookline. As one of the only kosher caterer/restaurants in the area, I am sure it delivers to Lexington.
If not kosher, you could call Via Lago in Lexington (781) 861-6174. They cater and deliver. Excellent baked goods and catered sandwiches, meals, etc. Great soups.
Barry's and Baker's Best are v good too.
Addendum: Butcherie is a kosher grocery store. Ruben's Deli is a kosher resturant. Both have websites, are in Brookine, and likely deliver to Lexington if you need kosher.
If not, all of the above suggestions would work, plus Zaftig's in Brookline for good deli as well.
My condolences to you and your friends.