The correct answer is: after the word “also” and after the word “cafeteria’s”.
The sentence could be improved for clarity and flow by placing a comma after "also" and "cafeteria's," as these help to set off additional information in the sentence. Thus, the revised sentence would read:
"She also wants her peers to have more say in the cafeteria's lunch menu."
Adding a comma after "also" and "cafeteria's" enhances readability.