Anna is busier in the last two chapters than the rest of the novel combined. She sparks an affair with Mompellion. She ends said affair. She delivers the Bradfords' newborn daughter, whom she then raises as her own because the Bradfords are ashamed of the scandalous circumstances of her birth.
See what we mean?
It turns out that the Bradfords want to frame Anna to cover their tracks, so she's forced to leave Eyam and find a new home. She plans to stay with Elinor's family at first, but at the last minute before arriving she changes her mind because it doesn't feel right: "I was not Elinor, after all, but Anna. It was time to seek a place where the child and I together might make something entirely new" (e.6).
Anna ends up marrying an Algerian doctor named Ahmed Bey, but not for love—she becomes his medical assistant. This is a big step for Anna, as she's both fulfilling her calling in medicine and becoming a more independent woman. It's the culmination of everything she's worked toward.
But that's not all—she gives birth to a daughter named Elinor, presumably from her encounter with Mompellion. While it might be weird to name your daughter after the deceased ex-wife of her dad, it's another way of showing us that beautiful things can be born from tragedy.