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.
If the heirs are only those mentioned in the question, and the deceased did not leave any other heir, then the inheritance is for the two direct sons by Ta’seeb (by virtue of having a paternal relation with the deceased and not having an allotted share, so they get what is left after any allotted shares have been distributed) that will be divided equally between them as the Prophet said: “Give the prescribed share of inheritance to those who are liable for it and the remainder [of it] is for the nearest male blood relative.” [Al-Bukhari and Muslim]
The children and the grandchildren of the son do not get anything from the inheritance as they are all prevented from it by the existence of the direct children (the two sons) of the deceased. Therefore, the inheritance should be divided into two shares, each son gets one share.
Allaah Knows best.