the hints are useless on this one . . . but I guessed it because I had written down the list of words from the lessons page . . . shouldn't have to do that to get it right with no previous exposure to the word!
Pronouns like 'mi' cannot be used by themselves, they must be attached to a verb. Furthermore, you want the subject pronoun (io) here, not the object pronoun. Think of the Italian as meaning 'nor I' or 'not even I' rather than 'me neither'.