The actions of the town drove her to do what she did and how they criticized her for not being social when they were the cause of her being ostracized. Also there is irony in the southern gentility and aristocracy. The people despised her for her inclusion in that high social class yet you need society to create this illusion of a higher class. You can't be atop the social hierarchy if society does not recognize you as part of that social hierarchy. A good example is where they despise her because she feels she is above them yet when she shows an interest in Homer Barron they protest because he is a simple day laborer from the north and not someone of high social ranking. Another bit of irony is that Emily purchases arsenic with the obvious intent of killing Homer Barron. She intends to do this because she learned that he is about to jilt her and leave town. The druggist who sells Emily the arsenic wraps it in papers and writes on it "for rats," which is exactly who she used it on in her mind.
Conflict-A Rose for Emily
Woman vs. self: Miss Emily battles mental problems, insecurities, fears, and paranoia. Rather than deal with these problems openly, she secludes herself--living in her own delusional world. Women vs. men: Miss Emily has problems dealing with the Southern aristocratic culture that views female status as based on her spouse's reputation and her role as social butterfly and a source of gossip in the community.