Is it permissible for a wife whose husband has passed away to dispose of his undivided estate, and to spend a portion of it on the children, and what is the ruling on the share of the adult daughter from the inheritance?

It is not permissible to withhold inheritance funds from the heirs and retain them, nor to spend from them without specifying each heir's share. Rather, they must be divided. A mature adult may dispose of their share as they wish, and for a minor, the court appoints a guardian to manage their funds and spend from them on their behalf. The mother does not have guardianship over the funds of her minor children.