Travel to Canada for COS to F1

[kabkaba]

My wife is currently in the US in H4 status.
She is expecting to start a new program from Spring 2011. We have received an initial entry I-20 from the school and she also has a valid F1 visa for the same school.
We are planning to change her status by crossing the border over to Canada and returning. We will do this either by road or air.
What I want to know is when she leaves the US, where should she return her H4 I-94? I want this information for both road and air options.

[txh1b]

Sometimes, ticketing agents refuse to take I-94 if the return trip is within 30 days. It will be an issue and in those cases, you need to let them know that your return status will be different and make them take the I-94.

https://www.immihelp.com/sample-paper-i-94-form/

It is your responsibility to ensure that your I-94/I-94W is turned in to Customs and Border Protection (CBP) at the end of your visit to the United States.

If you are departing by air, please turn the I-94/I-94W into the airline prior to departure.
If you are departing by sea, please turn the I-94/I-94W into the shipping line prior to departure.
If you are departing by land and you will not be returning to the United States within 30 days, please turn the 1/94/1/94W into the Canadian authorities when crossing the Canadian border and to a U.S. Official when crossing the Mexican border.