One of my favorites is Carolee Simpson Allison Aldrich (The Doctors). Both actresses to play the role - Carolee Campbell and Jada Rowland - brought such warmth and sweetness to the part to begin with - and it translated into mothering. Carolee stayed in a horrible marriage with an angry, abusive man (Dr. Dan Allison) because she didn't want to leave little Billy alone with him. After Dan died, Carolee and her next husband, Dr. Steve Aldrich, took him in.
Carolee also became a devoted mom to Steve's son from his failed marriage to Dr. Karen Werner - Erich. Karen was presumed dead for several years and Carolee and Steve fought for custody when it was clear that Karen was making Erich's life unhappy. Carolee saw Erich through everything from two heart surgeries, hospitalization from a tick bite, a kidnapping and the custody fight.
Carolee and Steve only had one child together - Stephanie. Though she has always been referred to more than seen, the love is obvious there too.
Through all the catastrophes (including being kidnapped by Steve's other ex-wife and stashed in a sanitarium, while being catatonic!) and being a working mom, Carolee has often been seen doing things like baking cookies with the kids and reading to them. Little scenes like that are so great - and so lacking in daytime today.