Is the deceased father's pension to be distributed among all children, or should it first be given to those in need, knowing that the mother lives with the questioner and her expenses are covered by this pension?

If the retirement pension is part of the deceased's savings from their salary, then it is an inheritance to be divided among all legal heirs, including married brothers. If it is a grant from the state, then it belongs to those designated by the granting authority from among the heirs, such as a wife, minors, or unmarried females.