in applying the preceding provisions of this subsection (and determining maximum family benefits under column V of the table in or deemed to be in section 215(a) as in effect in December 1978) with respect to the month in which the insured individual’s death occurs, the benefit payable to such individual for that month shall be disregarded. . 6. Effective date The amendments made by this Act shall apply with respect to deaths occurring in the first month beginning more than 90 days after the date of enactment of this Act.