Depending on where you live, it can be tough or impossible to go the grass-fed/pastured/wild route on $50/wk for two people. I've recently added back some rice a few days a week to stretch my food dollar, but honestly, the cheapest meat I buy is about $6/lb where it used to be about a dollar a pound for whole factory chicken or factory pork on sale. While this is somewhat countered by no more delivery pizza and hardly any more pre-made po'boys (maybe once a month), I spend a fortune on food in comparison to a year ago.
Do the best you can. Pattie provides an okay guideline except for the pasta, bread, and oatmeal. I'd spend that $3 on potatoes or white rice, or upgrade my coffee or meat. Frozen greens are a lifesaver and are usually cheap. Also, if you qualify for EBT (food stamps), they'll help.
"Right is right, even if no one is doing it; wrong is wrong, even if everyone is doing it." - St. Augustine