Agneta, Salander's mother, dies in The Girl With the Dragon Tattoo of a massive brain hemorrhage. She's a tragic figure who spent the last twenty years of her life in a nursing home. In Tattoo, we're not sure why Agneta, who is quite young, has suffered a brain hemorrhage. In Fire, we learn that regular beatings from Zala, her boyfriend and Salander's dad, left her brain permanently damaged.
It seems that Agneta did love Zala at one point, though whether she kept that love after all the abuse isn't revealed. We aren't sure if Agneta stayed with him all those years out of some kind of love, or whether she was powerless to flee the ruthless Zala and unable to get help as a result of Zala's involvement with the Swedish Secret Police.
When Salander meets Zala at his house in the woods, he tells her, "Your mother was a whore" (31.44). Salander says that her mother "worked as a cashier in a supermarket and tried to make ends meet" (31.45). We kind of get the idea that Zala (like Bjurman and Detective Faste) thinks all women are whores. In fact, it seems that Zala was the only man Agneta had a relationship with. Plus, her name is Agneta, which is derived from the Greek word meaning "chaste." But, we aren't here to argue about Agneta's sex life. Rather, we want to point out that the men in the book who go around calling women whores are the same ones abusing them. By their logic, labeling a woman a whore gives them license to abuse her.