She can contact the Finance Company and ask if they will allow her to take over the credit agreement. This will be agreed if she is in a position to afford the repayments. If the vehicle is registered in his name then she will need to get that amended by filling in the new owner section of the log book and signing it along with him. This needs to be sent to DVLA as soon as possible. There is a part of the log book - Section 10 New Keeper Supplement - which she must keep. If the new log book does not arrive in time she can use this to re-tax the car. Do not forget that she must have insurance in her own name for the car.