Whose money is it?

A few more details are needed. How old is your grandson? Why is he so bent out of shape over this? Is he thinking that this money should go directly to him so he can buy whatever it is he desires?

I would advise his mother to tell him the following:

You are a minor. You live under my roof and I am responsible for your well being as well as your public behavior. As such, I will spend the money your father gives me for child support in whatever manner I see fit, to be used for your benefit.

If that means groceries, or rent, or even car payment; that's what I will decide.

If you have an opinion, you are welcome to share it with me and I may be willing to discuss it with you. But the final decision is mine, and mine alone.

your daughter should tell her son money she receives from his father is for child support which includes everything from groceries to tennis shoes, school supplies, transportation, medical bills, housing, lights, water, TV(when available) or computer activities.  When you add it all up what his father pays in support might cover a small portion unless he is a Rockefeller.  Pocket money is a privilege and instead of raising hell with his mother, he should be helping her cope the best that he can.  He might try keeping his room clean and carrying out the garbage and being thankful for his mother and of course his father paying child support.  If that doesn't work then   may be his mother should send him to live with his father and let him cope with his rantings for a while.  All in all, the kid needs to grow up and see life as it really is.  He sounds like a spoiled child and use to getting what he wants. 

Vardon,  It sounds as if your grandson is acting out.  First of all it isn't his money, it's his mother's money to take care of him. (Food, a roof over his head, clothing, medical care, transportation, school etc.)  I'm sure there isn't enough money given to her to pay for all his expenses so she has to supplement those funds with more of hers.  Secondly she needs to get control of him!  Raising hell seems to indicate he is somewhat out of control.  Since he may be, maybe she can remind him she will have to spend some more of her money to take him to a doctor.