Jill: Hi Partyphile! Usually, I get invited to a party/event where I don't know anybody. Would it be alright if I bring a friend along?
Partyphile: Hey Jill! I know it gets very tempting to bring a friend with you to avoid uncomfortable social situations. However, most etiquette experts would tell you not to do that just because it messes up the host's day. It gives them another thing to worry about, another person to entertain, and another hitch to fix.
What I suggest you do is drop by the party, try to see if you have friends there, try to make new friends, or simply leave once you feel uncomfortable with the situation,
Of course, it is the host's duty to see to it that everyone is entertained and nobody feels out of place, but this can prove to be a gargantuan task for a huge celebration.