Assalaamu alaykum. Please calculate the inheritance according to the following information:
- Does the deceased have male relatives who are entitled to inherit: (A son) Number 1 (A grandson [from the son]) Number 4 (A husband)
- Does the deceased have female relatives who are entitled to inherit: (A daughter) Number 2
- Additional information: The son of the deceased died later and left behind a widow.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

If the deceased woman did not leave any other heir than those mentioned in the question, then her husband gets one fourth due to the existence of direct heirs (children). Allah says (what means): {But if they have a child, for you is one fourth of what they leave, after any bequest they [may have] made or debt.} [Quran 4:12]

The remainder will be divided amongst the son and the two daughters by virtue of Ta’seeb (having a paternal relation with the deceased and not having an allotted share, so they get what is left after the allotted shares have been distributed), the male twice the share of the female, as Allah says (what means): {Allah instructs you concerning your children [i.e. their portions of inheritance]: for the male, what is equal to the share of two females.}[Quran 4:11]

The grandsons do not get anything from the inheritance because they are prevented by the existence of the direct son. The Fiqh Encyclopedia reads, “The scholars of Fiqh agreed in a consensus that the grandson is among the heirs who take their share by Ta’seeb; he is prevented by the son and he himself prevents whoever is below him (such as great-grandsons).” 

Therefore, the inheritance should be divided into 16 shares, the husband gets one fourth, which is 4 shares; the son gets 6 shares; and each daughter gets 3 shares.

The share of the son is transferred after his death to his heirs, and his right is not eliminated by his death. His wife is among his heirs, but we cannot illustrate how his inheritance should be divided before knowing who all his heirs are.

Allah knows best.