I was going to ask the same as Juule. And agree with FallenMadonna.
Children in families where both parents work fulltime don't usually end up unfed and unwashed, you know. And most single parents manage to run a washing machine. So there seems to be something distinctly odd about this lady's son as well as the DIL. Why on earth is he letting his children get into a state where they may need the help of SS? And why should a 16 year-old do the work of a grown man? (though naturally, I approve of all children being taught to cook)
My husband works fulltime but still cooks dinner several times a week, does most of the washing-up and at least half the laundry. That still gives him time to knit dc's jumpers in the evenings . And we clean and tidy the house together at weekends. If your friend's son did only a small part of what he does, there is no way those children would get into the state described. Even if he works long hours, he could cook a stew for the freezer/fridge.
It seems clear that your friend is not capable of giving the full picture of what goes on in this family- she has edited her son's responsibilities out of it.