She was going to Vietnam on a family trip. I’d never carry that much cash. If you need easily accessible cash, get Traveler’s Checks. Actually, I haven’t used Traveler’s Checks in probably 40 years. Are they still available?
I don’t think Traveler’s Checks work anymore. When I travel I take a debit card and withdraw money there. Just do your research and stay away from the high-fee machines. Especially in Europe, if it’s blue and yellow, stay far far away.