what happened to the two healthy monkeys?

The two control monkeys lived because they weren't close enough to the infected monkeys to contract the virus,

The virus absolutely nuked the monkeys. It was a complete slate wiper. The only survivors of the experiment were the two control monkeys— the healthy, uninfected monkeys that lived in cages across the room from the sick monkeys. The control monkeys had not been infected with Ebola, and so, as expected, they had not become sick.