Find ethnic grocery stores in your neighborhood and buy in bulk. For e.g. Mung beans (http://indiaphile.info/guide-indian-lentils/) are very healthy and actually anti-inflammatory, cost fortune in regular supermarket, but if you go to Indian or Chinese grocery store, you will get them for almost $/lb. Learn how to prep them from YouTube or something similar.
Other thing you can look into is, Idly. This is also Indian (fermented) dish. Fermentation = probiotics.
/www.youtube.com/watch?v=PGYzSHGUDGo I wouldn't call it 'most' nutritious but lot more nutritious than many 'healthy' foods in the supermarket.
Same goes with few other beans. I was looking at some kind of beans at Costco and noted the price. Went to local Mexican grocery store and half the price.
As scum1 said, if your mom works 3 jobs a day, you do this homework and give your mom pointers, so all she is left with is, go to the store and pick the stuff you researched. Once the stuff is in pantry, you go preparing it or show your mom recipes so that she will make it.
(not judging you, yet) I was cooking almost full meal, by the time I was 14. My mom was going through pancolitis when I was 14 or so and she couldn't stand a minute before running to the bathroom. Our <bleep> PCP thought that she has heartburn and kept her on PPIs for 3 years until he learned that its something different.
Let us know your
location and may be locals can point you to some of the stuff. That will save your time researching this.
Offnote, learn to make Sauerkraut, natural source of probiotics. Cabbage is VERY cheap (I get it for $0.49/lb) Don't pay for them, make them yourself, not only tasty and healthy, but filling too.
Let us know if this thread doesn't help or you have any specific questions. We are here to help.
Off the topic,
how are you getting meds? If your insurance coverage is craptastic, take a look at GoodRx or community Health centers and ask about
340B (or similar) plans.