The county board of equalization shall have the authority and it shall be its duty to review any and all applications for homestead exemption which may have been filed with the county assessor and to make whatever order is necessary in order to grant homestead exemption to all applicants who are legally entitled to such exemption and prevent unlawful exemption on any property. If the board disallows any exemption which has theretofore been allowed by the county assessor, or changes the amount of exemption as allowed by the county assessor, such disallowance or change shall not be final until ten (10) days' notice in writing of said change shall have been given the applicant, and an opportunity for a hearing afforded on such disallowance or change.