Your Extension of Stay must be cancelled on the last day of working, all your family members must cancel their Extensions of Stay as they are based on your current Extension with support or your current employer.
You all need to apply for a new Extension of Stay with support of your new employer.
As in the days before Covid, the Non Immigrant B visa can only be Extended on basis of working in Thailand with Work Permit. As soon as the jobs stops, there is no reason to be inside Thailand. Only option is to go abroad and get a new type of visa.
Amazing, complaining about Thai Immigration because you are unable to decide which visa fits your purpose of stay and all Immigration does, is giving you 60 days longer to think about how to solve your problems. Remember all countries are opening up and flying around gets more easy every day.
Talk to the people who placed you in quarantine and tell them your immigration status. They can make a letter and collect your passport and fees to apply in your name for an Extension of Stay, but it must be done today.