Robert J. Lamb, 50, of Quincy, a retired Quincy police Officer, died Thursday at his home. Mr. Lamb joined the Quincy Police Dept. in 1969 and retired in 1991.He was educated in Quincy, where he lived his whole life. He graduated from Northeastern University in 1976. He was a member of the North Quincy Council of the Knights of Columbus and was active in Alcoholics Anonymous. He is survived by his mother Gladys M. (Pitts) Lamb of Quincy; a Brother, George L. Lamb of Brockton; A sister, Valerie A. Lamb of Bridgewater; and a nephew, Patrick M. Lamb of Plymouth. He was the Son of the late Leo J. Lamb.  A funeral Mass will be celebrated At 10 a.m. Monday at Sacred Heart Church, North Quincy. Burial will be In Mount Wollaston Cemetery. Visiting is from 2 to 4 and 7 to 9 p.m. Sunday at Sweeney Brothers Home for Funerals, 1 Independence Ave.