If you want a kinda logical justification about why Emma could do it: The inhumans were expecting Cyclops to be there. They were expecting him to lead the team to destroy the mist. Emma only showed them what they were already expecting to see so it was a lot easier than if she tried to show them something that was contrary to what they were believing.
That could justify it a little, for what it's worth. (and she did got a noise bleed out of it )