Joseph Nagy;78; of Monessen;died Tuesday;Nov.11;1997;at 9:15 a.m.in his home.  Born May 25;1919;in Rostraver Township;he was a son of the late John and Clara Drotos Nagy.  Mr.Nagy had lived in Monessen since moving there from Belle Vernon in 1954.   He was a member of Mary;Mother of the Church Parish;Charleroi.  Mr.Nagy retired Aug.31;1982;from the National Tube Company of U.S.Steel Corp.;McKeesport;where he worked as a welder.  He was a veteran of World War II;serving as a corporal in the U.S.Army.  Survivors include his wife;Josephine Bateman Nagy;with whom he celebrated 48 years of marriage on Jan.12;1997; one son and daughter-in-law;Joseph M.and Cheryl Nagy of Belle Vernon;  two daughters and sons-in-law;Vicki and Guy Hess of Belle Vernon and Karen and Robert Jurkiewicz of Charleroi;two sisters;Ann Berlin of Laguna Beach;Calif.;and Helen Feketer of Shaker Heights;Ohio;three grandchildren;Bobby Jurkiewicz;Melanie Nagy and Guy Hess Jr.;and one great-grandchild;Austin Hess.  Friends will be received Thursday from 2 to 4 and 7 to 9 p.m.in the Ferguson Funeral Home Inc.;700 Broad Ave.;Belle Vernon.  Family and friends will gather at the funeral home Friday at 9:15 a.m.to go to Mary;Mother of the Church Parish;Charleroi;for a 10 a.m.Mass of Christian Burial with the Rev.David Dzermejko;pastor;as celebrant.  Burial will be in Belle Vernon Cemetery.  The Ferguson Funeral Home Inc.is in charge of arrangements.