I would say to think first of small portions - a big lasagna (or pot of chili or whatever) is just too much for people to manage, especially if inactivity reduces their appetites.
What we do is go to the local discount or party store and get a bunch of small foil containers with lids and labels. The other thing we do is use either Lotsa Helping Hands or SignUp Genius to coordinate all those people who want to help. Both sites let you put in dietary restrictions (low salt, low fat) as well as preferences (they hate mushrooms and are allergic to nuts and chemo makes them unable to eat XYZ). The family can work with ONE or TWO coordinators and then direct all the "can I help?" requests to those people, who develop a schedule. Usually 3 days a week works well, and our families just put a cooler on the front porch or by the garage so they don't have to answer the door and socialize when, truly, they're wiped out. Volunteers can pick the days that work for them, and see the list of what other people are bringing and therefore avoid duplication.
Even if you have a moderaely sized recipe, divide it into portions you think are too small. Cover & label. If they aren't hungry, they'll make one portion. If they are hungry, they'll make 2. The others can go in the freezer.
Some go-to foods you can consider:
meatloaf, easy gravy or a tomato-based sauce on the side, oven roasted potatoes, green veggie (see below)
breaded chicken: tenderloins, breasts (cut in half or quarters, or smaller pieces to make "nuggets" if there are kids): dredge in flour, dip in egg, roll in some breadcrumb-type mix of regular or panko crumbs, wheat germ, wheat bran, mixed with crushed almonds or whatever else you have. Quick-fry in a light or healthy oil (olive, avocado, coconut or just canola), then finish in the oven.
Dipping sauces for above - use small salad dressing containers or tiny tupperware things. Recipients can choose what appeals to them. Suggestions include: soy sauce (with or without ginger or 5-spice powder added), honey/mustard (mix equal parts), marinara, Mexican (add coriander & cumin to a tomato base, even plain tomato puree)
Honey mustard chicken (no breading, just boneless breasts/thighs or tenders, with a mix of honey and any mustard you have, from yellow to spicy to grainy)
Sides: rice or rice/orzo mix with something added to the water (e.g. some tomato sauce if sending Mexican type food); quinoa salad with chickpeas (meat-free protein source) with any salad veggies you like (tomatoes, carrots, etc.), Israeli (pearl) couscous salad with peppers/cukes/onions/parsley and an olive oil/rice wine vinegar dressing.
Veggies: steamed broccoli with cheese; steamed green beans with almonds, roasted broccoli/cauliflower/small potatoes/asparagus/onions/root vegetables like carrots or parsnips (pick what you want - any 3 will look nice) and toss lightly with oil/salt/pepper and herb of choice - we use a lot of dill or Italian seasoning. Leave out the salt if there's a restriction. Pureed butternut squash - cube it, steam it for 20 minutes with garlic, puree in food processor, put in a baking pan or a foil pan, bake for 20 minutes. You can add a little sour cream and mix before baking, or put some grated Parm on top. Undercook everything a little to allow for more cooking during reheating.
Hearty soups: butternut squash with pears (yes, really - it's delish!), corn chowder with a crusty bread on the side, roasted tomato and red pepper. Do them in the crockpot, or roast things in the oven and then use an immersion blender or food processor to puree.