It's pretty rare for a Filifera to survive 0F. I haven't ever heard of them surviving those temperatures, but they have survived into the single digits in the desert southwest because conditions there are very dry and there is a lot of radiation from the sun which seems to benefit washingtonias recover from cold weather (and the washingtonias that survived were pretty big). Outside of the desert SW, I doubt Filiferas would survive below 15F without protection.
Good luck!
-Alex