Final answer:
The grey hair in 'A Rose for Emily' signifies Emily Grierson's continued presence and connection with her deceased lover, underscoring her inability to move on from the past.
Step-by-step explanation:
The discovery of the single grey hair at the end of William Faulkner's short story "A Rose for Emily" is significant because it suggests that Emily Grierson had a connection with the deceased character found in her house.
The grey hair symbolizes her presence next to him even long after his death. It reflects on themes of love, obsession, and inability to let go, highlighting Emily's refusal to accept the passage of time and change, which is a central theme in the story.