我妈妈肯定在家里，不可能在学校。用英语怎么说

Mother must be at home and can't be at school

I am sure that my mother is at home, not at school.

There's no way my mom is at school, she must be at home.

最楼上的犯了一个最常识的错误，没有动词！我的翻译和三楼的是一样的！

My mother must be at home.She can't be at school.
must be表示有把握的推测，不可能就是can't

Mother must be at home she can't be at school.