Are you able to get a CCW ? Can you carry at work ? A pistol or revolver carried on you would be much better. A gun in the car, as your walking to it after work, does no good.
In case you can't carry, (I live in California, and have family in New Jersey. I understand it is not possible in some areas,) I would suggest a pump shotgun. Add a light, and a shot shell carrier and there is nothing you cannot take care of in parking lot range.
A good flashlight should be a requirement for everyone anyway. That is the one peace of my EDC that is used the most. Second only to my keys.