The CBSA officer may/may not ask for proof of funds at the POE.do they ask for the fund she carry? ( at the port of entry) so if she holds a forex card ,no need to bring another fund right?
I would suggest your mom carries a combination of Forex Card and some amount of currency notes.... she must not keep any of this in her checked-in baggage.
Yes, you can withdraw money from ATMs using the Forex card.... as your mom's destination is Canada, you can top it up for CADalso is it possible to use and withdraw money from this card in Canada or any other place out side Canada?
Your mom can buy a one-way ticket as she has a Super Visa.... however, some airlines may not allow her to board the flight if she does not have a return ticket..... also the immigration officer may want to see a return ticket.I think I cannot change the return date if I do this I have to pay extra..
Tickets are valid only for one year..... so if your mom gets a 2 year stamp, the return ticket will not be refunded if you book non-refundable tickets.... it would be best to check with the airline (before you book) if they will allow you to cancel the return ticket when your mom arrives/gets a 2 year stamp.... and get a confirmation about this from the airline in writing.
My advice is to buy refundable tickets (with fare conditions that allow a date change for a fee)..... do not buy non-refundable tickets