Extending Benefits of the Policemen and Firemen's Retirement and Disability Act Amendments of 1957 to Widows and Surviving Children of Former Members of the Metropolitan Police Force, the Fire Department of the District of Columbia, the U.S. Park Police Force, the White House Police Force, Or the U.S. Secret Service Division, who Were Retired Or who Died in the Service of Any Such Organization Prior to the Effective Date of Such Amendments