Praise be to Allah.
What we understand from the question is that the son died during his father’s lifetime, so he does not have any share of inheritance. Based on that, the estate is to be divided as follows:
The wife gets one eighth, because there are offspring who inherit. That is because Allah, may He be exalted, says (interpretation of the meaning): “but if you leave a child, they get an eighth of that which you leave” [an-Nisa’ 4:12].
The mother gets one sixth, because Allah, may He be exalted, says (interpretation of the meaning): “For parents, a sixth share of inheritance to each if the deceased left children; if no children, and the parents are the (only) heirs, the mother has a third; if the deceased left brothers or (sisters), the mother has a sixth” [an-Nisa’ 4:11].
The two daughters get two thirds, because Allah, may He be exalted, says (interpretation of the meaning): “Allah commands you as regards your children’s (inheritance); to the male, a portion equal to that of two females; if (there are) only daughters, two or more, their share is two thirds of the inheritance; if only one, her share is half” [an-Nisa’ 4:11].
The brother [what appears to be the case is that he is a full brother] gets the remainder of the estate.
So the division of the estate among the heirs is to be done by dividing it into twenty-four equal parts.
The wife gets three parts, the mother gets four, the two daughters get sixteen – each of them getting eight – and the remainder, which is one part, goes to the brother.
And Allah knows best.