can you define express and implied permission to drive

If the person driving the vehicle had previously used the vehicle with the permission of the owner, then you may well have a case of implied consent, even though the owner did not consent to this particular use. If he owner of the vehicle consented to the use of the vehicle on this occasion, that is actual consent. Even if turns out there was no implied or actual consent, if your Mom has uninsured motorist coverage or the car she was occupying when she was injured has uninsured motorist coverage, she will be covered with that coverage.