What can we infer about gregor’s mood when he tells himself, “how about if i sleep a little bit longer and forget all this nonsense”?
gregor is calm.
gregor is hysterical.
gregor is fascinated.
gregor is fearful.

Gregor is calm.

Explanation:

According to the excerpt,

"Gregor then turned to look out the window at the dull weather. Drops of rain could be heard hitting the pane, which made him feel quite sad. 'How about if I sleep a little bit longer and forget all this nonsense', he thought"

Gregor didn't really lose his mind nor acted in a really emotional way when he realized what he was. In fact, he acted as if it was a dream and tried to sleep as if it was a bad dream from which he wanted to wake up later on. It wasn't until Gregor spoke that he started panicking:

"Gregor was shocked when he heard his own voice answering, it could hardly be recognized as the voice he had had before."

in my opinion i think it was not excessive at all. the maids turned against the queen in his absence, how could he ever trust them again? if he let them go they would surely spread the news of the suitor's deaths, which is much too risky. as for the suitors, they were selfish, rude, and greedy. the god's had apparently marked them for death, meaning odysseus made their death come faster.