I've done a couple versions of 'Silent Night' so you can impress your relatives after Christmas dinner ... one version is very stripped back, just the melody line and bass notes. It should be fairly easy even for those just starting down the path of finger style guitar. The second is a trickier, busier version, with a few different things going on ... for those who are further along.
Silent Night ... easy version
Silent Night ... trickier version
Don't forget the other two carols ...
White Christmas
Jingle Bells
Merry practice and for those who don't celebrate Christmas ... they're nice tunes anyway, and fun to play!