Money changers in town would appear to be of little use to the OP's daughter? She is overnighting at SBIA/BKK, on her way to Khon Kaen.
She should immediately try an ATM withdrawal, at an SCB or TMB ATM at the airport to make sure that works. I'd go for the max., be it some limit in CAD, or an ATM limit (500 CAD, so get 13,000 THB, or the ATM limit of 15,000 - 20,000 THB).
Having some pin money, 250 - 500 CAD, as back-up in case the ATM doesn't work, is a good idea. Given the lack of CAD buyers in Chum Phae or even Khon Kaen, it might a good idea to exchange some of this cash at the airport, even knowing that the rate is less than ideal. Again, if the ATM option is not available.
Either way, this cash gets her to Khon Kaen and Chum Phae where she can attempt to open a local bank account, preferably at a bank which has both a branch nearby, and an ATM. Using Streetview I see large-ish Krungsri, Kasikorn, SCB and even Bangkok Bank branches out on Rt. 201. Krung Thai (KTB) tends to be more dominant in rural areas of the North and NE. But check with the host family as they will probably be needed both for a recommendation, and to help get the account opened.
Once the account is opened you could do a SWIFT transfer, if that method proves to be the most efficient. Otherwise use the ATM, get cash, then deposit it in the local bank for use via their ATM.
https://www.google.com/maps/search/A.../data=!3m1!4b1
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