You might begin with a thesis statement about how both Emily Grierson in "A Rose for Emily" and the grandmother in "A Good Man Is Hard to Find" position themselves to influence their traditionally patriarchal societies, but ultimately, both women are led to violence because of their societal positions.
I would then construct two body paragraphs—one for each story. In the paragraph for "A Rose for Emily," you could examine the way Emily refuses to pay taxes when the men come to her house, leaning into the old patriarchal society's allowances. When men sneak around her property in the night to sprinkle lime because of the smell, Emily watches them from the window, "the light behind her, and her upright torso motionless as ... an idol." When the townspeople ask the Baptist minister to intervene when Miss Emily is seen "with her head high" in public with Homer Barron, Miss Emily gives the pastor a piece of her mind, and he refuses to return. In many ways, Miss Emily refuses to bow to the expectations of her patriarchal society. Yet her defiance comes with a price. Homer Barron represents her only real source of intimacy, and when he attempts to leave her, Miss Emily turns to violence. After killing Homer so that he cannot defy her wishes, Miss Emily keeps Homer's corpse in her home for decades. Bjerre points to the "aesthetic of extremes" which is often characteristic of the grotesque aspects of Southern Gothic Literature, and Miss Emily represents this quality. She is both revered because of her position and ultimately disgraced because she refuses to become the proper lady which her society asks her to be. Miss Emily therefore represents the need of humans to create happiness, even when the source of that happiness is less than ideal.
In "A Good Man Is Hard to Find," the grandmother also finds herself in a position to attempt to influence her patriarchal society. She mistakenly believes that verbally recognizing the Misfit will help her situation. After making this mistake, her son turns and chastises her to such a degree that the old woman begins crying. Unwilling to accept her likely fate, the grandmother tries to appeal to the Misfit's sense of justice and goodness, telling him that he is a "good man" and doesn't look like he has "a bit ... [of] common blood." She repeatedly attempts to appeal to the Misfit's sense of moral values, failing to understand that she is completely at the mercy of a man whose sense of justice is skewed. This man (and his male accomplices) holds all the power, eventually taking the grandmother's life even as she attempts to reach out in a maternal way, calling him "one of [her] own children." Bjerre examines the way "the possibility of redemption or salvation" influences Southern Gothic Literature, and in this story the grotesque ending reflects the price the grandmother must pay for her own shortcomings. Although a deeply flawed character herself, the grandmother cannot overcome the patriarchal strength that defines the ending of her life. The grandmother represents the human need for grace and the ability to transform under the unlikeliest of circumstances; even the Misfit recognizes that "she would of been a good woman if it had been somebody there to shoot her every minute of her life."