Adjustment of Status - I-485

So yesterday i received a mail requesting for initial evidence, "the petitioner/sponsor's household member on form I-864 or form I-864A must submit a complete federal income tax return submitted to the Internal Revenue Service(IRS) for the most recent tax year".
Here's the thing, my wife (USC) doesn't work and hasn't worked for a few years now, hence no tax filings for her as i am financially taking care of our family through my job; i'm on H1B. When i filed though, i did include a written explanation as to why my wife(sponsor) hasn't filed for taxes in recent years but i did include a letter from my employer indicating my employment status as well as annual income but i did not include my tax document/W2 for the most recent year which in this case will be 2014.
I'm confused as to what is required of me in this request for initial evidence but my guess is that they need a tax document from me for 2014. What document is required in this case and is this from my spouse or from me??????
This forum has been very helpful and i'd appreciate your insights and thoughts on this