Spanish help for a x-mas card

I’m writing out a Christmas card to a friend’s Spanish speaking family. I want to address the envelope to the whole family. Which is correct-‘La Familia Last Name’, or ‘Familia Last Name’? Would this also be the proper salutation to put inside the card?
ex: Querido _________
If anyone wants to dash off a little Christmas greeting suggestion for me, that would be great.
Thanks in advance.

Querida familia LastName

mala les desea una Felíz Navidad Y prospero año nuevo.