Just skip the placebo (the white ones she takes when she gets her period that are only "reminder" pills) and start a new pack. I do this all the time on Yaz. This is one of the advantages of taking the pill--skipping. She may have a bit of break-through bleeding (a small amount of spotting, usually) if she skips, particularly if it's 3 or 4 months in a row.
On the pill, you don't really have a real "period," per se. It's withdrawal bleeding. So skipping it is totally safe. She can also call her doctor's office if she wants to make sure. I don't know why this feature isn't on billboards! It should be.
Anyway, have fun on your vacation!