Mother is not like herself (slurring words, losing balance), but wont go to er. What do I do?

Call 911. If this is an acute situation (symptoms of recent sudden onset) there is a good chance she has had a stroke, in which case time is of the essence for treatment. She may be unable to understand what is gong on. This is a medical emergency and you should call 911 so an ambulance can take her to the er. It might be ok for you to take her to the er yourself, but if she won't go please get help.