**Martin Luther King, Jr., fought for social reform.
Here,I think the adverbial phrase means:-
For the Improvement of society as a whole.
Social policy is concerned with the ways societies across the world meet human needs for security, education, work, health and wellbeing. Social policy addresses how states and societies respond to global challenges of social, demographic and economic change, and of poverty, migration and globalisation.
Social reform is a change of social policy, targeting at an improvement of welfare.