The "me" in "Jenny and me are so excited," the "him" in "Kamal said him would try his best," and the "ourselves" in "Everyone needs to worry about ourselves."
Explanation:
The correct sentences would be "Jenny and <em>I </em>are so excited," "Kamal said <em>he </em>would try his best," and "Everyone needs to worry about <em>themselves</em>."