$300 certainly is not enough for three grown people. A 100 bucks s month isn’t enough. Food bank? I think you’d qualify.
I think I got confused because you said your husband’s mental health won’t allow him to use the stove so I wondered how he cooks. Mind you, one can cook without stove, it’s just a little hard. I still think that you need some type of care team to help all three of you to figure out some type of food routine.
Do you have a walker or a cane to get around? With a Walker you might be able to move around. I have a tiny kitchen but I could squeeze Walker there if need to and hold on to it for balance