My mom is planning to fly from Canada to the USA to stay with me for like 3 months, We currently have booked only a 1 way fare (because of a sale), will she need to have a return fare booked before her travel or can we book it after she arrives here in the US? She is a Canadian citizen. We were considering driving her back to Canada, so there really wouldn't be any proof of her return date. Any help is great appreciated!