First, are all your EPs/SPs patched? Seem to recall this was a glitch which was fixed with the Bon Voyage patch.
All I can offer is this:
Using Insimenator, or Inge's teleport shrub, or whatever teleport/summoner you prefer, go into an occupied house in the same 'hood as that of your Sim family (any occupied house other than the one belonging to the family frozen oin vacation) and teleport the Sims to that lot, then Save and Exit the game.
When you next run the game, the family should be back in their own house, and the vacation stopped.
HOWEVER, this includes an inherent possibility of permanently glorking the vacation lot where the freezing occurred, so if you choose to go this route be sure and make a back-up of your My Documents--EA Games--The Sims 2 folder first.
Also (though addressing a slightly different BV problem), found this:
http://forums.electronicarts.co.uk/sims-2/282108-help-stuck-vacation-sims.html#post4633334Might be worth a try, might not. I do not have BV installed, so cannot speak from any experience of trying what is offered at that link.