I'm at the end of my return. last year form 8879 was used but its not giving me that option to choose . what do I do?

Are you completing your taxes yourself?   I just reviewed my taxes I filed myself online and I did not need Form 8879.  My return kept the PIN that has been generated and used over the last few years.

https://www.irs.gov/pub/irs-pdf/f8879.pdf

Are you completing your taxes yourself?   I just reviewed my taxes I filed myself online and I did not need Form 8879.  My return kept the PIN that has been generated and used ovDiscarder the last few years.

https://www.irs.gov/pub/irs-pdf/f8879.pdf

You are preparing your own taxes and filing them yourself, you don't need Form 8879, which is used to authorize a third party to file your taxes. 

Yes, robb_411 is correct, Form 8879 is not used when you file your own tax return using TurboTax. 

Form 8879 is used to grant your paid preparer permission to file your tax return.