Like the previous responder said, you may want to clarify a bit more in order to get a more accurate answer to your question.
A social helper would be general term used to describe an individual person or group of people who are committed to helping or assisting others in need. I would also assume that this term could apply to anyone who has the intention of helping society as a whole.
I think an example of a social helper may be a teacher. Teachers assist students everyday, in many different respects. Not only is it a teachers job to teach content of a specific course, but it their responsibility to help in the formation of productive members of society. While teachers get paid to perform a specific job, many go above and beyond what they are supposed to.
Other examples of social helpers may be volunteers in numerous settings and social workers.