I shop on line for food items all the time and they are shipped to me. Walmart has a $35 minimum for free shipping. It is easy to spend $35. I order laundry soap, canned things like soup, spaghetti sauce, pasta, canned chicken, tuna, sardines, paper plates. You name it, I have probably ordered it. I shop at Costco online. I have ordered cheesy salmon patties, canned tuna, canned salmon, toilet paper, paper towels, vitamins, plastic garbage bags, ziplock bags, K-cup coffee. Costco has same day delivery service or two day shipping. I have ordered things from Target and Amazon. I have used Peapod delivery service. I get coupons all the time for free delivery or reduced delivery. The drawback of shipments is getting rid of the cardboard boxes and packing materials. For me it is easy to get the minimum to get free shipping. Sometimes I really don't need anything else but am just below the minimum. I will buy some cheap item like a nail file or a can of soup. You can also get frozen meat from QVC. I have bought chicken patties, ribs, pork patties (really good). Mostly with meat the price includes shipping. It comes in an insulated box with dry ice.
I also subscribe to Misfits Market which offers two size boxes of organic veggies. You can get a small one or a large one. You can choose weekly or every other week. You can postpone and restart as needed. If they are open to trying different fruits and veggies it would work out. If they are set in their ways, not so much. You don't know what you are getting from week to week and may not be familiar with some of the fruits and veggies. If they are foodies and like to try new and different things, they might like it. Fruits and veggies may be misshapen, slightly bruised, small or large but all are organic. You get your money's worth.
It might be wise for them to buy an upright frost free freezer so they can have a stock of things available. You can freeze bread, rolls and other perishable things. You could have them stock up on frozen veggies, frozen juices, meats and even shredded cheese. Some milks now have long expiration dates. When buying milk, buy two or three at a time paying particular attention to the expiration dates. Expiration dates sometimes go out two months.
If they eat ground meat for spag sauce or other meals, you could encourage your Mom to cook up 3 lbs, then break it into 3 one pound packages lay flat and freeze. Then when she cooks something, the meat can be thawed and used.
If you can get them set up with some of this stuff, minimum shopping can be achieved. Lots of stores offer delivery service.
I am on Medicare and get my drugs by mail thru Optum Rx. That might also be a help for them.
If they have pets, Chewy.com offers pet meds and prescription dog and cat foods. Vet has to approve it but that stuff can be mailed to them too. Not to mention dog and cat treats and supplies.
My hub is constantly cutting up cardboard for recycling.
One thing is that if you order a lot of canned or heavy things like laundry detergent, the boxes get too heavy. This is what I do when I have a big Walmart order. I break it up into maybe three $35 orders. So they don't pack the boxes so heavy. I try to jiggle the order so each shipment will be manageable when it arrives. I learned the hard way, if you order $100 worth of stuff they will try to jam it all into one shipment and it is a bitch to carry the box inside. So, I play the game and get 3 free shipments by breaking it into 3 orders equaling $105. Works for me!
Hope some of this might help!