staying in Murren Switzerland only 2 days...which transportation passes needed on the mountainside?

Are you staying anywhere else in Switzerland? That may impact the advice you get.

We're actually part of a Rick Steves tour going to Germany, Switzerland and Austria. The short stop in the Lauterbrunnen Valley area is the only place we'll need to figure out our transportation other than on foot. Since we want to hike as much as possible, we'll need to take advantage of the various modes of transportation to get back up and down quickly.

What are your tentative plans in the area (hikes/areas you want to visit). That will affect my recommendation.

We found the Bernese Oberland Pass to be ideal, but we were in Murren for a week. Not sure if it’s worth it for 2 days, but the convenience may be a factor. Virtually every time you go anywhere from Murren (except when hiking down to Gimmelwald) you’ll be using a cable car or train, and usually both. Example; to do the Mannlichen to Kleine Scheidig hike, you take the train from Murren to the cable car station, then the cable car down to the Lauterbrunnen valley. Then you take the train to Wengen and then another cable car up to Mannlichen. When you get to Kleine Scheidig, you catch the train back down to Wengen, then the cable car and train back up to Murren. And that’s just one day.

The whole Swiss Transport System is priced such that occasional use is expensive but regular use becomes good value. If you are only going to be here two days you are not going to be doing a lot anyway (and the weather might keep you in the hotel the whole day anyway if you are unlucky). So just buy tickets for the trips you want to do.