The avengers saw Wanda losing control of her magic, so they looked to the only person who could deal with it, Strange.
Dr Strange realized something really bad was going on, he was in disbelief...so he used his telepathy and mind wiped her, because he knew she was going to explode if she rememberd, he told the Avengers to get her help, and they really didn't do shit.
Then, the bug chick said a remark about Wanda's kids, and set her off.