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 deceased did not leave any other heirs except those mentioned in the question, then those who inherit amongst them are the wife, the mother, the son and the daughter only, and the other relatives do not get anything from the inheritance because they are prevented by the existence of the son of the deceased. Therefore, the wife gets one-eighth of the inheritance as her legal share due to the existence of the children of the deceased; Allaah Says (what means): {But if you leave a child, then for them [i.e. the wives] is an eighth of what you leave, after any bequest you [may have] made or debt.}[Quran 4:12]
The mother gets one-sixth as her legal share due to the existence of the children of the deceased as Allaah Says (what means): {And for one’s parents, to each one of them is a sixth of his estate if he left children.}[Quran 4:11]
The remainder should be divided amongst the son and the daughter 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 the allotted shares have been distributed); the male twice the share of the female as Allaah Says (what means): {Allaah 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]
Therefore, the inheritance should be divided into 72 shares, the wife gets one-eighth, which is 9 shares, the mother gets one-sixth, which is 12 shares, the son gets 34 shares and the daughter gets 17 shares.
Moreover, if the deceased had made a will as to how the inheritance should be divided and this is not in conformity with what is mentioned above, then his will is void unless the heirs who are harmed approve it on the condition they are adult and of sound mind.
Allaah Knows best.