She should call the pharmacy today and explain she will be out of town when her prescription runs out. The Pharmacist should be able to work something out under that situation with the insurance company, or just dispense a partial fill of the prescription early. Maybe a little harder if she needs them 2 weeks early than if she needs them a few days early. Insurance companies are usually more concerned about people trying to get more than a month supply at one time (they are afraid you are trying to bypass the co-pay).
If it comes to her having to pay out of pocket because the insurance says she's refilling it too early, she can send the receipt to the insurance, asking to be reimbursed along with a letter to explain why she had to fill it early - they may say no the first time, so she may have to be persistant and send it back a few times.