Wow, that must have scared you to death.  GPS my friend,  does she always, always take her purse.  Watch she can’t get off without help.  Alzheimers comes on quickly.  The first place she needs a full medical workup, talk to her doctor.  Sometimes older people can get a urinary infection and get very confused.  She should not drive, she will hurt herself.  I personally think when a parent is doing something that causes them to be put in danger.  You are now the parent, take away the keys, better yet kill the car.  You need to look at Alzheimer facilities and have her look at them before she is unable to make a decision.  You needed Power of Attorney yesterday.  join an Alzheimers support group, they have tons of knowledge.  Maybe Mom doesn’t have Alzheimers, but it will help to get information fast.   Hang in there Mom needs you.