I'm suggesting that you google pre-made meals then the name of the town they live in. There are many services these days that will make a meal for two (or more) then deliver them to their home, ready to go in the freezer. They are healthy and delicious. If you can't find them that way, try personal chef, then the name of their town.
Last choice: gift certificates. But make sure they come from places that do take out (chili's, for example). That will end up costing more than the premade meals.
Sending your own cooked food, while a lovely idea, is not a good solution for them. What if they are not home when it is delivered? A lot of good food gone to waste sitting at UPS waiting for them to pick it up.
Omaha steaks and so forth are good, but still requiring cooking. Again, pricey.
Other alternatives: Send them some snack foods, nuts, candy, crackers, trail mix, high end soup mixes, granola, dried fruit - in a box. No gift basket, but send the basket food stuffs. That will keep them happy for quite sometime. No perishables. Get the biggest box that the USPS offers and up to 70 of weight will ship at the same cost. Canned soups or canned chili. Noodles in a box for chinese, thai or japense.
Is that healthy? probably not. But I bet they'd enjoy it. BTW, as an ex-gift basket company owner, send something for the pets, too, if they have any. You've no idea how much that would make them feel good.
Your kind to offer to help.