if I live with parents can I claim that my grant was used for expenses for school?

Yes, you may be able to claim that your grant was used for school expenses even if you live with your parents. However, you must allocate the grant to qualified education expenses like tuition, fees, and course materials. If you use the grant for living expenses, it becomes taxable income

For more details, visit the IRS page on qualified education expense

Scholarships that pay for qualified educational expenses (QEE - tuition, fees, books and other course materials) is tax free.  Scholarship amounts that exceed QEE is taxable income, on the student’s tax return.

Room & board are not QEE. So, where you live is not relevant for claiming that your grant  "was used for expenses for school". 

 If for some reason you're wanting to say that some of your grant was used for room and board, yes you can do that even if you live at home.  That said, for more specific advice, you should explain what it is you are trying to accomplish.