This is an easy two-stage cache. At least calculating the final location will be easy. Finding the cache container may be a challenge. 
Bring your own pencil. Please replace the container as you find it.
The building at the cache listing location began its life as a Hotel. It was a stop on the Oakland-Sacramento railroad line of the Sacramento Northern Railroad. Here is a link to the Moraga Historical Society website describing this history. There was a nearby cache that is also related to the Sacramento Northern Railroad: Eastport (GCD0CD):
After Prohibition ended, it reopened as a bar. There was a state law prohibiting the use of the word “bar” in outdoor advertising, so it was christened the Moraga Barn. I bet that fooled a lot of people! 
It remained as a bar until 1995 when it closed for financial reasons. In 2006 it was reborn as the office for Canyon Construction, a local construction company who rebuilt the building. In 2015 it was sold.
To calculate the final cache location, go to the cache listing location (old Moraga Barn building) and note the three digit (ABC) street address on the west side of the building. Add the last two digits together: B+C=D and insert A & D into this location: N 37 50.07A W 122 0D.938 That is the location of the cache container. It is less than ¼ of a mile from the old Moraga Barn. Congrats to Moe311 for the FTF! 