Choosing the stance of Miss Emily is a symbol of the post-Civil-War South is a solid beginning for a high school essay. It’s a position most critics would agree with. The main advantage is that it agrees with what we know about Faulkner and the story. There are two main disadvantages. For a stance to be something you need to prove, it has to be something that is in doubt, i.e. that your readers might disagree with, or find new or original. Since the position is one generally accepted, it fails to meet the criteria of something that needs to be argued. The second problem with it is that it is too general. It’s a good starting point, but you need to narrow it down to some specific aspect of the post-Civil War South. Does she represent something good or bad? Is she a victim as much as an oppressor? You have a good starting point, but now you need to focus your topic more narrowly.