@rundocuri- I think the questions that will be on the security officer test that your nephew has to take will depend on the type of test it is. While the most common security officer test is one that students take during training, some companies also require potential new security guards to take tests before being hired.
I think that the types of tests given to students of security guard programs have fairly standard questions like the ones mentioned in this article. However, a test given by a company that is hiring security guards might have a combination of refresher questions and some that are specific to the company. Your nephew might also expect some questions about how to deal with possible security issues he might face on the job.
The best thing that you can do for your nephew to help him prepare for security officer testing is to reassure him. Make sure he studies the materials he learned in school, and suggest that he do some research about the companies where he will be looking for employment.