First off, I went straight to the source for this portion of my answer: My boyfriend has a houseguest for the next month or so, a 20-ish guy whose grandmother passed away last week. So I asked the houseguest whether my first inclination would seem weird to him - that inclination being to make a nice, hearty soup/casserole/pasta dish/whatever, and package it into several individual portions, suitable for eating immediately or freezing for later. J, the houseguest, said that he would find that (a) really normal, and (b) really welcome. (For the record, the houseguest is from small town rural Georgia, as am I, so that may color his response to my question.)
As for the reasoning behind providing food, even if your boyfriend’s friend isn’t grieving significantly for his grandmother, he’s a busy young man right now. Aside from all of the “death of a relative” duties that he has going on right this minute, there may have also been a period of time prior to his grandmother’s death during which the family was at the hospital or hospice or nursing care center and had no time to shop for even the basics. So, after a long day of comforting Mom or Dad, or attending a funeral or wake, there may not be any food in the house at two a.m. when he decides he’s really starving. That’s when the chili or ziti in the freezer comes in really handy.
In general, though, when there is a death in my circle of friends/family/close acquaintances, I borrow from my own experience in choosing how to help the family. After my father died, a business acquaintance dropped by with loads and loads of paper plates, napkins, disposable cups, paper towels, aluminum foil, dish detergent, bathroom tissue, and large cans of ground coffee. Everyone and her sister baked a ham or a banana pudding, but only that one person* thought of all these really practical things that a house in mourning needs. That gesture happened when I was a kid, but even today, I always try to bring these sorts of practical items - often without the casserole, but sometimes with, depending on circumstances.
*The person who thought to do all of this was the manager of the grocery store down the street from our house. What really blew me away about this kindness was that no one in my family really even knew him. He had apparently seen me and my brother - ages 9 & 10 when our father died - buying “real” groceries and carrying them home after school, because our mother was tied up at the hospital and there was no one else to shop during our father’s illness. The store manager also allowed us, more than once, to use one of his shopping carts to carry groceries home instead of lugging bags several blocks. I guess he heard about Daddy’s death, and donated paper goods and coffee from the grocery store. On the off chance that a former manager from Piggly Wiggly in Lyons, Georgia is one of this board’s readers, I never got to thank you. You don’t know how much my family appreciated that.