How do I kill this bass?

isolate that pitch, if you're a musician you should be able to pick it out on a keyboard, then use a frequency-note chart and notch it in the mastering chain, no need for a multiband here, it's a very good mix.
 
You think this could really be fixed in the master? just seem like the bass is really overpowering but when I take away volume it just dissapears right away.

I haven't ever looked at a frequency-note chart before. Not sure if I'm awesome enough to figure that out! Hehe.
 
Go to the offending instrument. Insert an eq with a q of 10 and set the gain to +18db slowly sweep it. When you hit the frequency in question it should be really obvious. Now turn that boost into a cut that sounds right. Fixing things in mastering is a compromise at best.