You do need to speak to an attorney right away. You have a limited amount of time to respond to the lawsuit after you are served, and if you fail to respond, it can be difficult to have any default that is entered against you vacated.
Based on your description, there are two initial issues to be addressed. First, if any of this publication activity was done in the course and scope of your husband's duties as a director of the HOA, then the HOA should be defending your husband from the lawsuit. There are also statutory defenses to liability for directors of HOAs that may apply to bar the lawsuit. An attorney would need to assess the applicability of these defenses to determine if they apply.
More importantly though, if the sum of your activity was merely publicizing the contractor's unlicensed status, then the contractor's lawsuit would meet the definition of a strategic lawsuit against public participation ("SLAPP"), i.e., an attempt to unlawfully quell the exercise of your free speech. California has a statute that allows victims of SLAPP lawsuits to file an initial motion to strike the lawsuit and recover their attorney's fees and costs for doing so if successful with the motion.
Again, all of this needs to be handled by an attorney. Please retain qualified counsel and ask the HOA in writing to defend you and your husband from the lawsuit.
If you are being sued, then you need to contact an attorney as soon as possible. There are no agencies that can step in and stop the retaliatory action.
If what you are saying is true, then you may have some good defenses against the contractor. You really need to talk to an attorney as soon as possible. Once you have been served with a summons, you generally only have 30 days to respond.
I am a general contractor and attorney that deals with construction cases.
I would be more than happy to discuss this with you. 909-455-1194 or 310-451-2424.
You need to consult with an attorney immediately. If you are able to show that the contractor's lawsuit is in retaliation to the complaint you filed with the Contractors State License Board and for posting accurate public information (his lack of a valid/active license), you could file an anti-SLAPP motion to have his case dismissed. If you prevail on the motion you may also recover all or part of your attorney's fees.