Lois I.Mazur;67;of 401 Parente Blvd.;Monessen;died Wednesday;March 12;1997;at 4:30 a.m.in Jefferson Hospital. Born Dec.24;1929;in Belle Vernon;she was the daughter of Joseph and Zelma Hammitt Kostelac of Belle Vernon;who survive. Mrs.Mazur resided in Monessen for the past 38 years;having formerly lived in Belle Vernon. She was a member of First Christian Church;Belle Vernon. She was employed for 15 years as a clerk and office worker for G.C.Murphy Company in the Tri-County Plaza. In addition to her parents;she was preceded in death by her husband;Theodore Mazur;who died May 28;1996. Surviving are three daughters;Mrs.Hugh (Sandra) Humpert of Livonia;Mich.;Mrs.Jack (Sharon) Nunns of Largo;Fla.;and Joyce Tatsch of Monessen;one sister;Mrs.Neil (Norma) Keller of Livonia;Mich.;11 grandchildren;14 great-grandchildren;one brother-in-law;Andrew Mazur of Beallsville;N.J.;and three sisters-in-law;Stella Fordanich of Southfield;Mich.;Sophie Plantis of West Bloomfield;Mich.;and Stephanie Branski of Garden City;Mich. Friends will be received Wednesday from 7 to 9 p.m.and Thursday from 2 to 4 and 7 to 9 p.m.in the Ferguson Funeral Home Inc.;700 Broad Ave.;Belle Vernon. Services will be held Friday at 11 a.m.in the funeral home;with the Rev.Donald A.Bowers;pastor of First Christian Church;Belle Vernon;officiating. Interment will follow in Belle Vernon Cemetery. Arrangements are being handled by the Ferguson Funeral Home Inc.