One of the biggest etiquette mistakes people make is bringing uninvited guests to a holiday party or event. If an invitation is addressed to you and mentions nothing about a guest, it is not acceptable to arrive with a quest. It doesn’t matter if it is your spouse, fiancé, child, or anything. If your host wanted you to bring along extra people, they would have indicated on the invitation or called you personally to extend an offer. If you arrive with uninvited guests it means more time and money spent by the host.
It is also not acceptable to call the host ahead of time to tell them you are bringing a guest. If you were invited, only you may attend.