Mags Newbie

Little is known about Mags Newbie, as she is deceased long before the start of The Sims 2.

Life Leading Up To The Sims 2
She was married to Bob Newbie Sr., as we see on her family tree. Together she and Bob Sr. had a son, the virtually infamous Bob Newbie Jr. (famed for his greasy clothing and bald head), who is intoduced in the tutorial of The Sims. Mags is the grandmother of Bob Jr.'s daughter, Brandi, who was the product of the marriage between Bob Jr. and his wife, Betty (Simovitch) Newbie. Mags is also the great-grandmother of Brandi's children; Dustin Broke, Beau Broke, and an unborn son.

Life in Sims 3
''Robert and Mags Newbie moved to Riverview along with their teenage son, Bob. Bob had a hard time adjusting to the move, but he’s found a new best friend to occupy his time.  

Reference
SimGuruRain Blog