My son's wife died and now he is left with three kids do you think....?

My son's wife died about a week ago after getting hit by a drunk driver. He has three boys ages 3,5,6 and he has been a mess he is barley taking care of himself let alone his three son's. My wife and i have asked him if he would like us to watch his three boys for a little while so he could have some time to himself to morn but that just made him irately mad at us for some reason. I am concerned for the three boys as well as my son but my wife and i are unsure how to approach him or ask him again. What would you do? How would you approach him? Advice?