What diagrams must contain in the SRS of NON-OO Project?
Can use case diagram, activity diagrams include in NON-OO SRS?
You should include every diagram that will describe best your system. I don't think there is a "MUST" here. It all should depend on the project you are working on and its specifics.
Think about what would you need to know about the system so that you would develop it the right way.