I assume your son's father died without an will. If so read the following:
(1) Upon the death of an individual who is survived by a spouse but not by any child or other descendant, the spouse is the sole heir. If the decedent is also survived by any child or other descendant, the spouse shall share equally with the children, with the descendants of any deceased child taking that child's share, per stirpes; provided, however, that the spouse's portion shall not be less than a one-third share;
She should have opened up a case in probate. Assuming she didn't, you can do so. In the alternative, you can send her a letter certified mail/return receipt or priority mail/delivery confirmation and demand his 1/2 of the proceeds of his father's estate. If the letter is unsuccessful, your only recourse is to seek court intervention. In any event, time is of the essence in this matter.
If your son is a minor, you should initiate the action. If your son is over 18, he needs to move forward to protect his rights.
