WHAT CAN I DO WITH THE DRINKS CART?

Notice that some letters are larger on the labels?

Let's only focus on those letters.

And rearrange them so they make sense.

Arrange the bottles to spell Mary Bodkin.

Remember the Mary Bodkin portrait?

This should tell you where you can use the numbers on the other side of the labels.

This is the code to the safe behind Mary Bodkin's portrait in the room under the billiard table.