OK - This is the rule: You DO NOT use an apostrophe when signing your name on your holiday cards. Never. Ever.
(Courtesy of Kate Brannen)
Q: What if my last name ends in a “y”?
A: Add an “s.” Do not add “ies” or an apostrophe.
Merry Christmas from the Murphys.
Q: What if my last name already ends in an “s”?
A: Add “es.” Do not add an apostrophe.
Season’s greetings from the Simmonses.
Q: What if the end of my last name normally functions as an irregular noun?
A: It is not irregular when it is part of a last name.
Happy holidays from the Hoffmans. Warm wishes from the Wolfs.
Q: What would adding an apostrophe do?
A: It would hurt Tiny Tim make your last name possessive.
Q: Is there ever a reason to add an apostrophe?
A: Only if you want to make your last name possessive.
Q: Why do people add apostrophes?
A: I have no idea.