Is a Stranger in a Community Exempted from Jumu`ah Prayer Due to Fear of Violence?

This depends on the seriousness of the violence in the environment. If one fears for his life and he is likely to be a target of the violence, this can be an excuse for not going to the Jumu`ah congregation and in that situation, one should perform Dhur Prayer instead.

But there is need to check the situation first  by asking fellow Muslims of that environment about how safe one will be and they will guide him to the best solution. Alternatively, one may check if in a local area he is going to there is a small number of Muslim men to form a small Jumu`ah congregation.