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, sallallaahu ‘alayhi wa sallam, 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 wife gets one-eighth as her legal share due to the existence of direct heirs (children); 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 daughters get two-thirds as their legal share, as Allaah says about the existence of a number of daughters (what means): {But if there are [only] daughters, two or more, for them is two thirds of one’s estate.}[Quran 4:11]
The mother gets one-sixth as her legal share due to the existence of direct heirs (children). 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 after the division of inheritance shall be given back to the mother and the daughters.
Therefore, the inheritance should be divided into 120 shares, the wife gets one-eighth, which is 15 shares, as her legal share, the mother gets 21 shares as her legal share along with the share(s) that she gets back after the division of inheritance, and each daughter gets 28 shares as her legal share along with the share(s) that she gets back after the division of inheritance.
Finally, it should be noted that the matter of inheritance is a very complex issue, so a mere fatwa, which is an answer issued according to the question, is not enough. Rather, the matter should be taken to an Islamic court to look into the case and investigate as it might be that there is an heir who would not be known except after investigation, and there might also be a will, debts, or other dues that are not known to the heirs. It is known that these rights come in priority over the right of the heirs in the inheritance. Therefore, the inheritance should not be divided without resorting to an Islamic court, if any, in order to fulfill the interests of the dead and the live people.
Allaah knows best.