Is it permissible for a mother to deprive her male children of their share of the gold from her inheritance, claiming that she helped them with their marriages?

The mother's will to disinherit her male children from their share of the gold is invalid. The sons have the right to their legal share of it. The fact that she helped them with their marriages does not justify disinheriting them from the inheritance. Favoring one child with a gift for a legitimate reason, such as marriage, is permissible, but one cannot stipulate disinheritance from inheritance in exchange for marrying them off.