When in doubt, bring them in. However, some fig trees are hardier than others. For example, Beall and Smith are NOT hardy trees. And there are a few others in the same boat. I spent my entire weekend moving trees around between greenhouses and my garage. Yesterday, I ran out of time and left a few Smiths out. Will they die, no. But the cold will impact its growth rate next year. The good news is it will warm back up to 50 today but cold again tonight.
So, my rule of thumb is, when in doubt, winterize.