What elements in the description of the room in the final section in "A Rose For Emily" shape our understanding of the story?
The overwhelming image is of dust. Dust can be viewed in a number of ways. Literally, the room has been so long closed up and neglected that it has become a haven for the dirty particles.
Dust is symbolic too. Think of the biblical verse, "dust to dust." Death is not prettied up, as in the parlor where "the town (had come) to look at Miss Emily "beneath a mass of bought flowers." No, here, with Homer's corpse rotting on the bed, death is a real thing. Dust is a reminder of mortality.
Furthermore, dust is indicative of the way Emily herself had become neglected and ignored by the townspeople. As the story progresses, Emily becomes more and more isolated, the metaphorical dust piling up on her soul. No one cared to sweep it away, as she couldn't bring herself to care about her home.
Consider this description as the room is surveyed:
"A thin, acrid pall as of the tomb seemed to lie everywhere upon this room decked and furnished as for a bridal: upon the valance curtains of faded rose color. upon the rose-shaded lights, upon
the dressing table. upon the delicate array of crystal and the man's toilet things backed with tarnished silver, silver so tarnished that the monogram was obscured"
As readers, we see Emily's tragic life truly for the first time along with the characters who had the misfortune of entering her bedroom.