Mariah Archer and Lukus Williams are engaged to be married in December in Carlsbad, Calif.The bride-to-be is the daughter of Gardnerville residents Wayne and Felicia Archer.She is a graduate of Douglas High and Boston University where she earned a bachelor's degree in psychology and a master's of public health. The groom-to-be is the son of Blythe, Calif., residents James and Kathy Williams.He attended Palo Verde High School and grew up in Blythe. He is a graduate of San Diego State University, where he earned a bachelor's degree in journalism. The couple met at the San Diego Center for Children where …