Hi there!
Answers are :
☆ Go over to the car to find out more about the problem -> We dont know what is their intention. So, dont do it.
☆ Offer to help the person with the problem -> Still no use. Offering doesnt help, we need to help them in action.
☆ Ask the person to come over to talk -> That's okay. Not a problem.
☆ Walk away from the person -> Never do that! It will be rude.
So, the answer is to ask the person to come over to talk.
Hope it helps !