The woman known as "the Mother" was a high ranking member of the Three Families.
In 2011, the Mother met with an agent of the Families, Jilly Kitzinger, to show her the northern end of the Blessing in the underground structure built around it in Shanghai. During the meeting, she asked Kitzinger to rewrite history in the new era of the Miracle in ways that would be favourable to the Three Families. (TV: The Gathering)
To protect the Blessing from further interference, the Mother and another high-ranking member of the Families in Buenos Aires planned to bury it by destroying the surrounding structures in both cities. After the incursion of Jack Harkness and his Torchwood allies, the Mother was taken hostage by Oswald Danes, who was wired with explosives. Despite offering him wealth and opportunities to satisfy his criminal urges, Danes and the Mother were killed when he detonated his explosives.
Behind the scenes
Frances Fisher was credited as playing "the Mother Colasanto" on the BBC iPlayer website, implying a blood relation to Angelo Colasanto and his granddaughter Olivia, who had said the families refused to work with them. However, Jane Espenson told AfterElton in her Jane's Take for The Blood Line that the character had only ever appeared in scripts as "the Mother".