"Social science is the study of how people interact with one another. The branches of social science include anthropology, economics, political science, psychology, and sociology.
Social scientists study how societies work, exploring everything from the triggers of economic growth and the causes of unemployment to what makes people happy. Their findings inform public policies, education programs, urban design, marketing strategies, and many other endeavors."
See:
https://www.investopedia.com/terms/s/social-science.aspAs far as I can tell most social sciences would require you to study statistics - because you need evidence for your arguments.
With economics, it entails the most mathematical modelling out of the social sciences (as far as I know), so you would need to know quite a bit on maths. However, it doesn't mean that all of your assignments and exams are maths based; most of them would require you to write essays.
The borderline exception would be mathematical economics, which is essentially maths for economic subjects.
If you study FM, then you should be fine studying for even the more quantitative economics degrees (e.g. mathematical economics). There is no maths in law as far as I know.
Which subjects you choose is still your choice, but if you're only looking into law and economics as options for your degrees then you can still go into them with Maths, FM, Physics, and Econ. Whether you choose history or econ to go into law or economis is inconsequential (for most universities except for possibly 2 or 3).