Just found this thread and might dip in more frequently!
Do you have more than one bottle?
Where has it been stored the last 20+ years?
Do you know the producer?
I ask these because '93 was a rubbish year in St Emilion generally; it should have probably been drunk years ago, but it might just be ok, depending on your answers. Apologies for the bad news but better knowing now than being disappointed in november.
I could suggest getting something from her birth year (2002) however this was also a rubbish year in europe generally. Apart from Burgundy which, if you can find anything, will be outrageously expensive. Other options could be champagne or dessert wines, again neither will be cheap. Apologies for more bad news.
So, my sensible alternative for your daughter's 18th would be to get a good bottle of something you know she likes*. Talk to your local merchant, they should be the wine equivalent of your LBS - friendly and helpful.
it's actually a 1995 Chateaux Canon
And I've also got this one for my son (this has turned out to be better vintage, although I paid the same for each)
Both have been wrapped in brown paper and stored in a dark dry cool place. I'll let you know on the 6th November what the Chateaux Canon is like! (she prefers Gin so I'll buy her a nice bottle and we'll guzzle the wine)