If she is Thai nationality… she only need her Thai passport fly to Thailand. She don’t need any visa. Also if you are going with her U only need US passport and air plan ticket.
yes my husband is American. I don’t know if different country different rule or not. They require both US driver license , passport and fill out W9 form.
I’m not sure if it allow to buy one way ticket or not. Im moving back to Thailand this summer with my son. We both have Thai passport and I bought one way ticket.