My son had one topic when he wrote his NHS essay last year. They didn't have 5 items to choose from though. Maybe the essay portion varies by school? He had a fair amount of service hours, nothing outstanding, and he got in.
Actually every school determines their own application/admission process. DS was admitted in February. He needed to have at least 100 service hours, create his "college resume", have at least 3.5 cum gpa, and write an essay about one of the greatest achievements in his life.