No it wasn't. The party that night was at Fleet and Priscilla White's house, several miles away.
I don't know how to take this piece of info. I know at the time of the murder I clearly heard that there was a Christmas party at the Ramseys house. Not just heard it once but numerous times. Was that just another mistake in reporting by the media? Or had there also been a Christmas party there some other night and that was a confusion to the issue. If true, this is the first I heard of it.