Ava waits until he's well on his way to getting into the building before she goes to take her position by one of the abandoned cars nearby. It doesn't fully help her view of the hiding ghouls and she doesn't expect it to, but it gives her enough cover while she readies herself for when Deacon begins to shoot. It also sets her up for a straight shot once they will eventually start headed for him.

Carefully, she checks her ammunition and pulls the gun out, taking careful aim at the first ghoul she can see. Then, all she needs to do is wait for Deacon to begin shooting.