I'm sure most of the income from the Corp activity was already passed through on her W-2, right?  🙂

In my old(er) age, I just decline these "janitorial services" opportunities.  But I would start with the bookkeeping.  If she didn't know what kind of entity she was, she likely also didn't know that she needed to be doing payroll.  My guess is you'll find the can of worms is that she just took money willy-nilly out of the Corp.  With a C Corp, are those wages or dividends?  You can't fix the 1040 until you know the amounts and flavors of income from the Corp.  Even if things were done correctly assuming it was an S Corp, (reasonable salary for time spent plus owner distributions as appropriate), any distributions would become taxable dividends from a C Corp (i.e. subject to taxation at both the corporate level and the individual level) instead of tax-free basis reductions from an S Corp.

If you're lucky enough, you'll find that she set up a Corp but then proceeded to just run all of the money through her personal bank account (a.k.a. Sch C).

In any case, get the facts and then ask your tax questions.  At this point, don't assume anybody knew what they were doing or are competent enough to tell you what actually happened.  Follow the money and find out on your own what actually happened.  Accountants politely call this "trust but verify".  My translation of the phrase has always been "you have no idea what you're talking about, let me see your business records."

Rick