Answer: 1. who, 2. Me, 3. him, and 4. whom.
Explanation: we use who, whoever or I, when we are referring to the subject of the sentence, in sentence 1, we are talking about Mr. Williams (and he is the subject) so the correct option is "who". We use whom, whomever, him, or me, when we are referring to the object of the sentence, in sentence 2 Agnes is the subject and "Ellie and me" is the object. In the third sentence "you" is the subject" and "him" is the object. And in the last sentence "you" is the subject and "the guests" is the object so we use "whom".
