Have a local civil rights lawyer look into your case. False arrest is a civil rights violation and a Section 1983 lawsuit can be brought if the facts are right.
If an investigation can prove the police did this arrest and held your husband overnight needlessly and with zero cause or for an improper reason, then your husband has a good argument for a lawsuit.
False Imprisonment or False Arrest is a civil matter ( a tort) which can be the basis for a lawsuit subject to the laws of your jurisdiction. I would also suggest that you look into any requirement to make a "tort claim" which is required before suing a governmental agency. Most jurisdictions have the forms online and they are simple to fill out. The filing of the claim is a prerequisite of filing a civil suit and often have short time windows. Please check out the requirements in your state either with an online search or contact a local attorney. Many offer free consultations and will be able to talk to you about options and maybe give you some peace of mine. Good luck.