In addition to the very good oppositions identified by the previous two posters, you may also be interested in exploring a less concrete opposition in William Faulkner's short story "A Rose for Emily": the known versus the unknown.
This opposition structures the entire story. The collective narrator and the reader are not in on the complete truth from the story's start. As many posters have commented in other, earlier enotes.com posts on this short story, the reader -- much like the townsfolk -- has to piece together information iand make a number of assumptions n order to make sense of the story.
One previous poster on your question identitied the opposition of downstairs versus upstairs. Couple that with the opposition of known versus unknown and you pretty much have the core structure of this Southern Gothic tale,
Male vs. Female: our collective narrator(s) are male, and Emily is female.
South vs. North: Emily, a Southerner, marries Homer Baron, a Northerner
Past vs. Present: Emily lives in a fantasy world of the past, where her father and the Old South are still alive. The house, too, used to be the grandest on the block; now, it is a decrepit, smelly eyesore
Appearance vs. Reality: Emily appears to be an eccentric miser, but in reality, she is mentally disturbed, a necrophiliac.
White vs. Black: Emily, white, only lets one person inside her home, a black handyman, who is basically a mute--showing the powerlessness of blacks in the South.
Aristocracy vs. Working Class: Emily thinks she is of the aristocracy, the Chevalier culture of the Old South, a Southern Belle; she marries a working class construction worker from the North because no one else would have her.
Gay vs. Straight: Homer is obviously gay; who knows what Emily is... But it's an odd marriage, to say the least.
Upstairs vs. Downstairs: guests used to be admitted, but only to the downstairs parlor; no one was allowed upstairs to see the unholy bridal suite.
The main contrasts that are shown in "A Rose for Emily" relate to the social classes and changing world of the south. Emily's family used to be the upper echelon of society, at the top of the social ladder. They were rich, they were respected and held in awe, and they were exempt from typical regulations and expectations as a result. Emily would only marry the best, and their family would only have the best. However, this type of thinking was quickly becoming outdated and old-fashioned in a world that was modernizing itself. The old upper-class of the south, which had been centered mostly around wealth from plantations, was a time period that was gone. Emily's family was the last of the last of these types of families in the town.
Throughout the entire story, Faulkner constrasts Emily's haughty attitude with the reality of the situation. Her mind and behaviors are stuck in the past with the elitism of her family, whereas everyone and everything around her had moved on. The town became modern, but she stayed old-fashioned. The town remodeled itself, but her and her house remained the same, becoming victims to age and wear, ending up decrepit and a joke, an old relic in a town that liked new things. The contrast fuels much of the storyline and tension--Emily's refusal to align her expectations leads to her dismissal of the townspeople who demand taxes. Her stubbornness in regards to Homer Barron leads to his demise and her isolation. Her snobbery, contrasted with the lack of it in the social classes in the town, lead to her ostracization and alienation. These contrasts are a crucial part of the plot and suspense. I hope that those thoughts helped; good luck!