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 has no other eligible heirs except those mentioned in the question, then his wife is entitled to one-eighth of the estate as a fixed share because of the existence of the children of the deceased. Allaah, The Exalted, says (what means): {…But if you leave a child, then for them is an eighth of what you leave, after any bequest you [may have] made or debt…} [Quran 4:12]
The four daughters get two-thirds of the estate as a fixed share. Allaah, The Exalted, says about the share of the 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 remainder of the estate is also divided among the daughters (i.e. it is returned to them in proportion to their original shares). Allaah, The Exalted, says (what means): {…But those of [blood] relationship are more entitled [to inheritance] in the decree of Allaah. Indeed, Allaah is Knowing of all things.} [Quran 8:75] Moreover, the Prophet said: “If someone dies leaving some property, then the property goes to his heirs...” [Al-Bukhari and Muslim]
Thus, the estate should be divided into thirty-two shares; the wife gets one-eighth of them (i.e. four shares) and the daughters get the rest (i.e. twenty-eight shares) as their fixed shares in addition to what is given back to them as there is no other heir who is eligible to inherit it; so each gets seven shares.
Allaah Knows best.