This is really a personal ethical question. Muslims have never really fully agreed on the nature on Hinduism. Some consider it a religion that leads people to the divine and others consider it to be superstition and idolatry. Maybe there is truth on both sides as most religious have pluses and minuses and different ways they are practiced.

Anyway, if you think this person is doing something good by going to temple, or if you wish to follow the golden rule "do unto others as you would have them do unto you", then give them a ride. And if you disapprove of them going, then don't give them a ride. 

This is assuming you are giving a ride to a friend, neighbour, relative, etc, and you are not working as an Uber or taxi driver. If you are working as a driver, most drivers do not interfere with where their passengers are going and just take them there.