All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
If your sons are from your wife who died then they inherit her as she is their mother. If the wife died and left two sons, a husband and a mother, then the husband has a fourth of the inheritance, the mother a sixth of and the remaining inheritance is to be divided among the two sons, each one of them gets a half.
Your sons do not inherit their grandmother as they are the sons of her daughter and a grandson from the daughter does not inherit unless the dead does not have any eligible heir in which case they (i.e. the grand children) are entitled inherit.
Allaah Knows best.