What is a major social issue (problem) occurring in Rwanda (Central Africa) and
social factors that contributed to this problem along with poliices
and activities?

You may want to investigate the plight of refugees in Rwanda:

"The United Nations World Food Programme (WFP) and the United Nations
High Commissioner for Refugees (UNHCR) are increasingly concerned
about the deteriorating conditions of tens of thousands of refugees
and returnees in Rwanda as WFP runs out of funds to provide them with
food aid.

WFP urgently requires US$5.5 million to provide 9,000 tons of food
assistance to some 60,000 people until the end of this year.

Food stocks to feed 54,000 refugees, mainly from the Democratic
Republic of Congo and Burundi, and thousands of Rwandan refugees who
are now returning home are quickly running out. By June WFP will have
exhausted all its cereals. Following late donations, a new consignment
- enough to cover cereal needs for two months - is expected to arrive
at the end of July, but it will be finished by September."

http://www.reliefweb.int/rw/RWB.NSF/db900SID/EVOD-6CSCD5?OpenDocument

Ok, that is a good website. I like it, however it does not say why
there are so many refugees and returnees in Rwanda? What happened?

Hi, here is a site that gives some background:

http://www.unitedhumanrights.org/Genocide/genocide_in_rwanda.htm

You can find many more with Rwanda massacres OR genocide