Is it permissible for children to take their due share from their father's money that is available to them, which the father inherited from one of his deceased children, in the event that he deprives them of it, and do minor orphaned children have a right to this money?

Neglecting children's rights and falling short in fulfilling them are considered major failings on the part of a father. Nevertheless, he must be honored, treated kindly, obeyed in what is right, and accompanied in goodness, even if he is unjust, as Allah Almighty says: "And We have enjoined upon man [care] for his parents - good treatment" and "and to parents, good treatment."

As for financial entitlements from years of service: if they were deducted from the deceased employee's salary, they are an inheritance for the legal heirs. If they are a grant from the company, then they belong to whomever the granting entity specified. A father's ill-treatment does not permit taking anything from his wealth without his permission and consent.