What is the tone of the story "A Rose for Emily"?

For most of the story, the tone is humorous. The narrator lets us see how eccentric Emily is and how the townspeople delight in following her actions. In a discussion of point of view, the study guide says this about the tone:

Regardless of identity, the narrator proves to be a clever, humorous, and sympathetic storyteller. He is clever because of the way he pieces the story together to build to a shocking climax. His humor is evident in his almost whimsical tone throughout what most would consider to be a morbid tale. Finally, the narrator is sympathetic to both Emily and the town of Jefferson. This is demonstrated in his pity for Emily and in his understanding that the town’s reactions are driven by circumstances beyond its control.

After Emily buys the poison, the tone turns suspenseful. Just what does she plan to use it for: rats? her cousins? Homer? herself? One might even think the final scene to be horrific.