#1 - Do not ignore them, and don't offer excuses - build a wall and stay behind it at all times! http://www.jehovahs-witness.com/topic/428170001/fading-beginners-guide
#2 - Demand that they give your husband the name/s of his accuser/s, and tell them straight that you do not dignify someone's gossip by replying to it. Your husband should tell them that he wants to follow the Scriptural counsel on how to resolve this misunderstanding. (Matthew 5:23,24 & Matthew 18:15)
#3 - If they try to assert "their" involvement in the matter, your husband should respond by telling them that he will write to the Service Department at Bethel to ask for their opinion on how this should be properly dealt with, and he does not want to discuss it further until he's received their guidance!
Don't give these idiots any information whatsoever - because they will pervert it and turn it against you both.