Is it permissible to sell a house that the father endowed for every needy one of his children, male and female, when it has become old and is on the verge of collapsing years after his death?

Firstly: It is permissible to make an endowment (waqf) for one's descendants. The condition stipulated by the endower must be adhered to. If he stipulated that it be only for the needy among them, then that must be followed.

Secondly: If the endowment becomes defunct and requires repair, it is permissible to sell part of it to restore the remaining part. If this is not possible, the entire endowment should be sold, and another endowment should be purchased with its proceeds. The supervisor (nazir) may incur debt to repair the endowment, which will be repaid from its income, or sell part of the endowment to repair the rest if the income is insufficient and borrowing is not feasible.

Thirdly: If the endower did not specify a beneficiary after his children, and if they die or there are no needy among them, the endowment becomes of indeterminate destination (munqati' al-jiha). It then devolves to the endower's heirs, becoming an endowment for them, unless otherwise stipulated.