What you can do is you pay for the juice(billing address) and have them ship it to your mom(shipping address). It could be a problem since most Canadian vendors use EMT as a form of payment and American vendors shipping over the border is a roll of the dice. She is either going to have to learn to buy juice off the internet, find a local B&M store inwhich are pretty well located in large major centers or have a friend do her buying for her. She should have no problem taking the PV over the border but its the juices that can cause the hassles depending on how much your bringing over and the mood of the border guard. Importing juices into Canada is a grey area for customs and most border guards just don't know and they take it just cause they can. I personally get a lot of my vape gear from the US but I buy all my juice from Canadian juice vendors so I don't have to worry about customs other than maybe pay some duty on my gear.