Besides guilt, the narrator and townspeople also feel some admiration for the woman. During her life, they were somewhat afraid of her because she represented to them vestiges of an aristocratic past that still influences the town even though it has become modern. By the end of the story, the narrator shows an understanding of time and age in one of the most beautiful passages of the story. He says that the old folks came to her house upon her death, "talking of Miss Emily as if she had been a contemporary of theirs, believing that they had danced with her and courted her perhaps, confusing time with its mathematical progression, as the old do, to whom all the past is not a diminishing road, but, instead a huge meadow which no winter ever quite touches...." Even in her death, Emily remains alive in a romantic sort of way to the town--she was never quite human because she seemed "above" them, and for that reason she didn't seem quite dead, even while she lay on her bier. This romance, however, is shattered when they break down the door to enter her room and discover what her inability to come to grips with her own past did to her.
You have one excellent answer. Miss Emily is an icon in the town...at least what she stands for is the icon--last surviving antebellum lady, daughter of a Civil War hero and affluent family. She is to the town what famous movie stars and professional athletes are to us today...we admire them, but they are untouchable. They do not always make the best decisions, but we want to be them.
The town, on one hand, admires her. On the other hand, they are curious and angry that she gets special favors--no taxes are paid by this woman, and no one bothers to ask her why her house smells so horribly (you don't ask a southern lady why she has an odor).
Yes, she murdered Homer. Perhaps she is mad. More likely, she was lonely, and so steeped in a tradition of the southern lady that she couldn't allow Homer to muddy her reputation.
I think the narrator (do not confuse the narrator with the author) feels a great deal of guilt about the town's treatment of Emily. She may be "mad" and "murderous" but her isolation and loneliness is what has driven the woman over the edge. The narrator describes the town's attitude toward her in the first part of the story...she is the daughter of a Civil War hero, an "other" virtually untouchable (in more than one sense of the word) and unknowable (or so they choose to believe).
Roses are traditionally the symbol of love but also a funeral flower that, historically (before embalming) covered the scent of death. We can think of the rose as one that Emily offered to Homer, or he to her, but the life of a rose is short-lived. Or we can think of the townspeople offering her a rose on her casket, as an act of contrition and rememberance.
She is not a "murderous madwomen". The attitude is sympathetic because the narrator know her past and her family's past. Emily was oppressed by her father and in a way held prisoner to his will. The narrator know this and that psychological illnesses run in her family so she was driven to feel the need to love and be loved. It is the lack of intimacy and friendship in her life that drove her to her unfortunate old age and eventual death.