I would like to know the cheapest route to take for the following if I am staying in Wengen and having a Swiss Pass:
1. Going to Jungfraujoch
2. Going to Murren
The route to the Jungfraujoch is explained here; from Wengen it's 25% off with your Swiss Travel Pass.
Traveling between Mürren and Wengen is for free with your Swiss Travel Pass. You can either travel via Grütschalp/Winteregg or by bus via Stechelberg. Both variants are covered by your pass.
Please check the Swiss Travel Pass validity overview for details.