Elements of Suspense: the Landlady

What are the elements used by the writer to create suspense in the story?
  1. Character of the landlady - She seems "off her rocker", odd, peculiar, too motherly, she is prepared for a visitor
        - She seemed terribly nice. She looked exactly like the mother of one's best school-friend welcoming her into the house to stay for the Christmas holidays."

        - Is peculiar, overdoing things like giving Billy a welcoming warm smile, offering the room at a fantastically cheap price and becoming terribly nice like a motherly figure, helping Billy with a coat etc

        - She is telling Billy   to sign the guest book ”because it’s the law of the land, and we don’t want to go breaking any laws at this stage in the proceedings, do we?”

        - and there are only 2 names in the guest book: Christopher Mulholland from Cardiff. The other was Gregory W. Temple from Bristol.   “I’m almost positive I’ve heard those names before somewhere. Isn’t that queer? Maybe it
          was in the newspapers. They weren’t famous in any way, were they?
          He was positive now that he had seen them in the newspapers – in the headlines.
          “Left?” she said, arching her brows. “But my dear boy, he never left. He’s still here. Mr Temple is also here. They’re on the third floor, both of them together.”
          These are the creepy details that create suspense in story as to how are they there on 3rd floor and no signs of them in the   boarding house.

        - She also asks for Billy age at several times and says he is perfect one.

        - She also has stuffed animals which she has herself embalmed. ““I stuff all my little pets myself when they pass away.”

        - She is also prepared for a visitor: “But I’m always ready. Everything is always ready day and night in this house just on the off-chance that an acceptable young gentleman will come along. And it is such a pleasure, my dear, such a very great pleasure when now and again I...