It was difficult to find fault with Jan's succinct but very accurate assessment of the situation. This was really bad and Wanda figured it could only get worse. Drained as she was, Wanda would still have to do something, especially after Jan's accusation. She did have this under control until someone else let themselves get bitten. The origin came from inside, there was no way something had made it through her barrier from outside. That part, at the very least, wasn't Wanda's fault.
"The magic thingee-" Wanda began, a little defensively, in answer to Jan's question and raised a thin magical barrier between the flames from Clint's arrows and the retreating backs of fleeing civilians, "Was trapping everyone." The energy holding back the fire wasn't going to last long, but the people trying to escape wouldn't have to add burning to death to their list of dangers and the barrier would hinder the lumbering dead.
Wanda turned her attention from the fire and back to Clint when she heard him yell and her first instinct was to fire off a bolt of energy at the creature on top of him, not focusing on what exactly it would do but just on hitting it so it would get off him. The monster exploded outwards. Oops. Clint was alive, Wanda would argue later. The gore covering him was beside the point.