Reasons for the use of "hardly a soul" and "four years ago" in the conversation between Framton Nuttel and Vera in "The Open Window" are:

1. To set the scene: The phrases are used at the beginning of the story to establish the setting and create a sense of isolation. "Hardly a soul" suggests that the area is sparsely populated, while "four years ago" implies that it has been a long time since anything interesting has happened.

2. To build suspense: Vera uses these phrases to build suspense and create an eerie atmosphere. By emphasizing the emptiness of the area and the lack of recent activity, she sets the stage for her ghost story.

3. To manipulate Framton Nuttel: Vera uses these phrases to manipulate Framton Nuttel's perceptions and make him more susceptible to her story. By emphasizing how quiet and deserted the area is, she makes it easier for him to believe that a ghost could be lurking nearby.

4. To foreshadow the twist ending: The use of "four years ago" is significant because it foreshadows the twist ending, where Vera reveals that her story is a fabrication. By mentioning a specific time frame, Vera hints that there is more to the story than meets the eye.

In conclusion, the phrases "hardly a soul" and "four years ago" are used in "The Open Window" for several reasons, including setting the scene, building suspense, manipulating Framton Nuttel, and foreshadowing the twist ending. Together, they contribute to the overall atmosphere and plot of the story.

In the chapter " The Open Window" written by Saki, Mr nuttel had nerve disorder and his doctor recommended to go to village. His sister went to the village three years ago and she gave him a letter of introduction to Mr nuttel as he never went to the village. When Vera asked that whether Mr nuttel knew a person of that village, Mr nuttel told he didn't but he knew Mrs Sappleton.