No, that's not how manslaughter works. If she had intended to kill Mrs Ward it would have been murder.
As it was, she committed an unlawful act that was likely to do harm. She did not intend to kill Mrs Ward but she did, through an unlawful act. And she is judged to have understood that that act - intimidating Mrs Ward and forcing her into the road - was unlawful and potentially harmful.
An accident would have been her attempting to move over and make room, misjudging and colliding with her. Or accidentally dropping her bag and Mrs Ward hitting it.