回複：我的理解, 她得先拿到加拿大簽證, 再進入美國時(開車過關)

There are two things you have to consider. First, certainly, she needs a Canada visa first. Second, if she surrenders her I-94 while entering Canada, she will get a new one when coming back to the US. However, whether or not she could get another six months depends on the immigration officer. If she doesn't surrender her I-94, she will definitely not get another six months because she can just come back to the US with the current I-94.