Is it necessary to keep our daughter on our vehicle insurance policy as a driver although she is now at college and will only drive the car 4 or 5 times per month-our premium doubles keeping her on?

Yes! Even though she might not be driving the car often at all,( let your insurance company know this, your premium might be cheaper) if a wreck should happen, she's not on the insurance, the ticket will serve as her at fault, with no insurance.