What's up with "Mother's Day"?
Mother’s Day is expressed as singular possessive because Anna Jarvis, its founder, insisted that it “be a singular possessive, for each family to honor their mother, not a plural possessive commemorating all mothers in the world.” President Woodrow Wilson also used this spelling when he made it an official holiday.
But rather than worry about what Anna Jarvis intended the holiday to be, why not tell your mom (or moms) that you love her (or them)?
If you insist on being grammatically right, here’s a tip:
But what really matters is that this sentiment gets across to your mom (or moms):