If you agree to provide care for your grandfather, make sure you both agree upfront that in the event you don't want to continue, you can quit. And if you will be living with him, make sure you have money to move out when you quit. I read quite a few stories about live-in caregivers being stuck with the job even though they HATE it, but they can't move out because no one else will take over, or they have no place else to live.
Do you have any training or experience in care giving? Can he afford to pay you? You would need a proper contract in place. Where would you live? What degree of care does he need? What are his health problems?
So many questions to answer before proceeding.