This is the code I'm getting from my obd2 reader and I've changed the front 2 o2 sensors, plus have changed the Mass air flow sensor within the last 2 years. I bought bosch o2 sensors, do you think one of them is defaulty? 94k miles maybe the back o2s need to be replaced?

 

Replace the back ones too.
Then reset the code and see if it comes back.
Also double check your work on the front ones.

 

If you had read your code properly you would see that a 150 is a circuit malfunction on the front 02, passengers side.
You should have replaced all 4 at the same time.