In her early life, Emily seems to have lived under the mantle of female oppression that existed prior to the Civil War, a sort of antebellum concept of what it means to be a Southern belle, despite the fact that this era had passed. The way in which the townspeople thought of her family shows this. The narrator says,
We had long thought of them as a tableau, Miss Emily a slender figure in white in the background, her father a spraddled silhouette in the foreground, his back to her and clutching a horsewhip, the two of them framed by the back-flung front door.
Emily's existence is legitimized by her father's, but, apparently, during his life, "None of the young men were quite good enough for Miss Emily," and she found herself single and thirty, even the subject of some pity in town, especially when word got out that she had no money. She was so disempowered, so oppressed by her experiences to date, that she could not accept the fact of her father's death and denied it for several days.
However, Emily later becomes empowered, in a way, as a result of her fear of being abandoned again. She begins a relationship with Homer Barron—a Yankee, a "'day laborer'" of whom her father would have greatly disapproved—despite Barron's public insistence that "he was not a marrying man." Evidently driven by her fear of being abandoned again, Emily poisons him. Rather than accept a man's decision for or about her, she is empowered to make her own decision; it certainly isn't a healthy or legal decision, but it does show the change in Miss Emily.