The only error in the sentence:
One of the resolutions made by the committee was accepted by the authorities with one of the additional consideration discussed during the session.

He became rich overnight. What part of speech is 'overnight'?

The nightingale is a singing bird. In this singing is a/an --

I Came home after the rain -----.

The Doctor took the round in the hospital. Here 'round' is a/an ---

Alumni is the plural from of