The first absent mother would be the mother of our main character Scout Finch. She died when Scout was two, so she never knew her. However, growing up in an era when girls wore dresses and practised their manners on a daily basis, it is obvious that Scout did not have a female influence around the house. Scout did have Calpurnia around to help keep her in line, though, unlike our other motherless character.
Mayella Ewell had no female influence whatsoever. No word is ever mentioned about her mother or where she was. Instead, she was in charge of seven other children/siblings and a father who was drunk most of the time. Because of her lack of female influence, Mayella gets herself into a mess of trouble by tempting a Negro and then accusing him of raping her when she gets caught trying to kiss him. Instead of coming clean, Mayella only proves to the court how pathetic her life really is, and continues to point her finger at Tom Robinson.
The other theme dealing with parenting is the theme of abusive fathers. Boo Radley's father was the first one introduced. Although not physically abusive, he forced Boo to remain indoors for the rest of his life, turning him into a recluse and the town Bogeyman. We finally get to see what time and distance from others has done to Boo when we get a glimpse of Boo in the final chapters.
The last abusive father is Bob Ewell. He abuses Mayella physically. In fact, Atticus proves that Bob is responsible for the injuries she blames on Tom. Without a woman around, Bob not only abuses Mayella physically, but also sexually. In Tom's testimony he says that Mayella told him "what her papa do to her don't count."
With these two themes, the contrast is made between the type of fathers these men are to the kind, responsible character of Atticus. Alone, he is able to teach his children what true courage is as well as how to really understand other people. So these situations draw to light how great Atticus truly is to his children.