Both may potentially be "offset" (legally not "garnished") from your refund. For your SS overpayment, it depends on whether you or your son is deemed liable.
For child support, if you filed a joint return with your husband, the IRS will initially attempt to take the entire refund as if it was his money. You probably should have filed Form 8379, Injured Spouse Allocation, with your return so the IRS can determine how much of the return is your husband's money to go to child support vs. your money which should be refunded. Now, you'll probably have to wait for official notice of the child support offset, then file the 8379 separately to get some of it back
