Sarah's mom is an acient artifact of the 70's complete with flare bellbottoms and wild hair tied back with a bandana. She is seen very little in the series reletive to other characters and does not seem to hold much signifigance in the second arc of the comics either but she does play one important as playing a sort of devil's advocate for Julie's thoughts surrounding violence and the world around her. Unfortunately Sarah's mother probably checked out mentally to a large degree after her husand killed himself on one day and since then she's been on a mission to make sure that her outcast and depressed daughter doesn't follow in his footsteps. She is not very adept at understanding her daughter so it's quite difficult and so she sends her to her social worker friend, Julie, to help smooth things over.
Sarah's mom is a liberal thinking feminist much like Julie they share many philosophies in common but also have enough differences to argue with each other every week as she picks Sarah up from counciling. She seems to be good friends with Julie despite their very different lifestyles. Sarah's mom remains oblivious to all that is happening in Sarah and Julie's outbacks throughout the series and is probably much happier to be that way, oh well.