If she's overly concerned, she could mail them to you. Note I said "mail" because the USPS is the only service that will knowingly transport ashes. But the Domestic Mail Manual says they have to be sent registered mail. We shipped my FIL home in advance and had no issues from the PO. He was in a metal box with the US Army seal and nameplate. We figured mailing was the easier way than having to keep track of him and dealing with airport security.