Just a quick rundown:
C comes first, in 1969. It’s an imperative language / procedural language.
C++ comes about in 1979. At first called C with classes it implies what it is, it adds quite a few things to C – for example object oriented features. C++ is basically an enhancement to C in the beginning, until the features are so many and covering that the language stands on its own.
Objective C was born in 1983 and it extends C – many of the new features are SmallTalk inspired, and object oriented.
C# is not based on C, but inspired by C (big difference) and came about in 2001 as the newest kid on the block. At first the name of the language was COOL – which stood for C-like Object Oriented Language. The intention was to create a language that was object oriented, was C-like, but without the flaws found in the current major programming languages.