There is another possible case - that parents are very ignorant. If so they need to be forced to attend the nutrition training showing them how they can get healthy and cheap food.
Taking children away should be the LAST resort.
Food stamps shouldn't be redeemable for anything except basic foods and staples - classes for training should be the province of volunteers and hand-wringing do-good agencies.
I will agree that protective custody is a last resort, but I see a LOT of need for last resort action. If state wards grow up to be criminals, what's the difference? Many would have had the same fate with lesser options in their mother's care anyway.
Every Social Services Department has pamphlets on "good nutrition".
That, of course, is not to suggest that every poor person is on Welfare...but at least nutritional material is available there.
Additionally, most if not all areas have food banks to supplement food stamps.
Cost is less than turning the kids over to the state to support too.