Monther in law gift to son in law

Gift to specified relative is exempt. Otherwise aggregate gifts from non-relatives is exempt upto 50000/-. Beyond that, total amount is taxable.

son in law is not specified relative of mother in law.

Gift can be received from any lineal ascendant or descendant of the spouse of the individual. Mother of spouse (mother in law) is lineal ascendant. Hence mother in law is a specified relative.