If your friend is in such hard times, I'd try to look up local food pantries. Local businesses and churches can donate to or run these food pantries, and you can get pretty decent food. (e.g. locally the wheat bread on the shelf is untouched apparently needy people here are picky enough)
Yeah, assuming this isn't just an ultra frugal grocery shopping exercise, I'd also add, help your friend get on food stamps. A family of 3-5 can gross up to $2,008-$2,836/month and and be eligible. For July 2012, the USDA estimates the cost of feeding a family of four (with kids ages 6-8 and 9-11; younger kids would cost about $20/week less) at their "thrifty" level to be $144. I'm sure some families--especially those with one non-working parent, who has the time to comparison shop, meal plan, etc.--can beat that, but the gulf between that and $30 is pretty wide.
But if this is a frugal shopping exercise, and your friend's time is that tight, I would say that $30 and a few hours of your weekend is the best. Glancing at my local circulars, this would be my shopping list:
- dried black beans (1 lb: $1.50)
- rice (20 lb: $8)
- eggs (3 dozen: $3)
- chicken leg quarters (12 lbs: $8)
- yams (3 lbs: $1)
- green beans (5 lbs: $4)
- bananas (8 lbs: $4)
- onions (2 lbs: $1)
This are NYC (albeit on-sale) prices, so you'd probably be able to do even better elsewhere.
Presoak and cook the beans; brine and roast the chicken legs with the yams; mash the yams; take the leftover chicken fat and sautee the onions with them, then add the green beans; make a big pot of rice and beans. You could load it all up in a big foil tray, or portion it out into smaller containers/servings and take it to your friend. It's about 26 lbs. of food, so depending on their appetites/family size, they could get a full week's dinner out of that. The eggs and bananas are extra.