Dean didn't have a problem with Emily going up in front of them. Dean believed that Emily was capable and that she could handle herself if a vampire came at her. If this was a nest then the vampires would be indoors, packed together like a football team of bloodsuckers. Dean was already brandishing his stake, his body coming to a crouch when he heard the noise that Emily had heard. Dean frowned, not knowing what it was. It didn't sound like anything he was familiar with.
"Get down," he whispered, speaking to Emily who was still standing. They were in front of an abandoned house that was near the edge of the park. Dean could hear the noise from inside and moved so that he was towards the side of the house and away from the porch. Right when he ducked behind one of the bushes with Sam and Emily the front door opened and one of the vamps came out to light up a cigarette.
Dean wasn't sure what sort of vampire they were dealing with. It was hard to tell but at the same time it worried Dean because of the enhanced vampire hearing. They were close enough that even their breathing could give them away so Dean held his and signaled for Emily and Sam to do the same. The vampire started to walk towards them and Dean remained perfectly still, his fingers gripping the stake as Dean watched the vampire turn away and lean against the porch's railing.
Dean didn't waste a moment - he stood up quickly from his hiding spot and with a single strike he drove the stake into the vampire's back, right through the heart. Dean was pleased to see the vampire combusting into a heap of dust that littered the porch.
"Our night might have gotten easier," Dean said, moving back and smiling at both Emily and Sam. "That house is probably full of them. We can pick them off one by one."