Need an obit look up for the following person.

John McCormack, born 13 June 1896; died Dec 1978; Last Residence - 11379 Flushing, Queens, NY; SSN - 091-05-3327; Last Benefit - 11951, Mastic Beach, Suffolk, NY; State SSN Issued - New York (before 1951)

Above info was found on US Social Security Death Index. What does "last benefit" mean? No familiar with USA records.