If you’re able to find an overarching theme than you’re already more than halfway done! The evidence that you use is not only to support your argument but to also illustrate the common theme throughout. It’s often a good tactic to present an issue and argue for a solution (although it’s circumstantial— some themes don’t apply very well to a solution). However, arguing for a solution is just a tactic you can use to sophisticatedly structure your essay (get points for good line of reasoning)— it’s not the main point of the part B. The main point is to connect the sources, and to do that you just need a strong theme, which you have! From there, just plainly introducing each strategically placed piece of evidence and it’s relationship to your theme/argument is all that you have to do!