(a) No State law providing for presumption of death shall be applicable to claims for benefits under laws administered by the Secretary. (b) If evidence satisfactory to the Secretary is submitted establishing the continued and unexplained absence of any individual from that individual's home and family for seven or more years, and establishing that after diligent search no evidence of that individual's existence after the date of disappearance has been found or received, the death of such individual as of the date of the expiration of such period shall be considered as sufficiently proved. (c) Except in a suit brought pursuant to section 1984 of this title, the finding of death made by the Secretary shall be final and conclusive.