According to our Family Code, if there is still a minor a part of the family and who is dependent on the support from the family ie dwelling, education, transportation etc. You cannot sell the land and its improvement as this is contrary to public policy and order. You would deprive that person of his rights to dwelling which is protected by our Constitution.
But if the any of the members of the family does not have this kind of support and independently live separately from the family dwelling, your mother can sell the land and its improvement. Provided all of the members consented of such sale.