Hello and thank you for your question. I will be very pleased to assist you. I'm a practicing lawyer in England with over 10 years experience.
May I clarify with you please what evidence there is that you gifted your house to your daughter? Presumably you signed a transfer deed to place the property in her name? Is there anything else that confirms the same was a gift?
Regarding the IOU to your son in law, did you and your husband both sign this and your SIL has a copy?
From what you say do I understand correctly that your husband has now essentially changed his mind about the gift / IOU and wants to take a share of money out of the property for himself?