My mother should never pick a man over her family. This process involves people from both sides removing the labels they have given to the other side. It also involves thinking of a logical way of dissolving their differences. If this doesn't work a mediator can come in and tell them what needs to be done to get peace. I mean peace in his private life, family, friends, but especially for good luck.
Peace is only possible if the feuding parties both seek it.
Closed-mindedness is also detrimental to the pursuit of harmony. If the two parties are not sensitive to each other's principles, disrespect and the feeling of being disrespected will always be prevalent. The only result of this is war. I'd participate in bringing peace to my neighborhood by being the person to lead people away from the dispute. I wouldn't look down on the people involved, but instead try to convey to them that war and revenge are pointless.