Maybe getting the hell out of there was the worst thing they could have done. Wanda would mull it over in retrospect, curse her own stupidity, blame herself even more, hope they understood. You went in blind. A teleportation was never a sure thing and the distance between LA and the West Coast headquarters was enough that she had make a single stop for a jump to the building. Wanda could know where she needed to be, she could imagine it, she could get there. What she couldn't account for was what else was in that place and in this case it was zombies, a huge herd of them, and the Avengers and a handful of civilians they'd rescued landed right in the middle of it. It should have only been a momentary pause, she could have got them right out with a deep breath and a focus within seconds of hearing that first guttural growl. She couldn't account for what anyone else with them would do, either, and when a man they'd rescued darted away in terror she couldn't just go.
"Stop!" she shrieked and reached out but it was too late, the horde had a hold of the man and was ripping him to shreds before she could get the energy barrier around them to protect them. This was horrifying, even worse than the refugee center. Wanda was running out of energy fast, she needed a moment to shore it up, to refocus. A moment was a luxury they didn't have.