Not sure about the Canadian laws, but in the states I would suggest that he keep a tape recorder or video camera hidden in the house and on until he catches her instigating some form of violence on him or the child. Then take the child and leave after filing for a protective order and divorce (if he was married to the mother). Or stay in the house and have her served with the order keeping her away from the house.
He will have to have good proof that she is the violent one, however, before he does this.
Nobody will believe him otherwise. The courts are still under the impression that 95% of all domestic violence is propagated by the man, when the real number is more like 55% instigated by the woman. This evidence will also be useful in disputing the inevitable false accusations a woman like that will use to gain advantage.
Check out the FRTC website at http://www.deltabravo.net/cms/plugins/content/content.php?content.359. There is a PAS Information Archive there with over 30 articles on Parental Alienation Syndrome. One of those articles discusses Malicious Mother Syndrome. This woman sounds like a good candidate for that.