Do you think food stamps would make the parents buy food? Most likely not. I'm certainly not a do gooder sometimes I wish I was. I'm just being realistic. The parents need fixing. It's not about the price of food everyone knows that it's about bad parenting and parents that are lazy drug addicts or have mental health issues and who don't look after their children.
In principle I've nothing against the idea of food stamps, I'm just not sure how effective they are in practice... For responsible parents it would seem like a nanny state thing, and for irresponsible ones I can see a black market emerging where €20 in food stamps = €10 in cash.