12. Sale of homestead land, public land law

In 1950, the Bureau of Lands issued a Homestead patent to A. Three years later, A sold the homestead to B. A died in 1990, and his heirs filed an action to recover the homestead from B en the ground that its sale by their father to the latter is void under Section 118 of the Public Land Law. B contends, however, that the heirs of A cannot recover the homestead from him anymore because their action has pre­scribed and that furthermore, A was in pari delicto. Decide. (5%)