Answer: The plural of cameo is (3.) both "cameos" and "cameoes".
Explanation: The word "cameo" is a noun generally used to refer to a brief part in a film, a TV show or a play performed by a well-known star. The plural of "cameo" is both "cameo" and "cameoes". In other words, both forms, "cameo" and "cameoes", are accepted when someone needs to refer to more than one "cameo". However, people tend to use more "cameos" than "cameoes", which is still in occasional use but it is now considered to be dated and unfashionable.