Actually, even if my mom files Single or MFS, she still owes the same amount. I know, I redid her taxes either filing as "Single" or "MFS". Like I said before, she has already been audited. If she wasn't allowed to file as "Single", she would have been told by the person who audited her that she filed her taxes incorrectly. Also, the tax guy (not the auditor) who did her taxes is extremely careful when it comes to taxes, and he told her to file as "single". I'm not a tax expert, but I'm guessing my mom can file single. I don't know much about my mom's story with her husband. Lastly, I'm not sure how this is perjury and/or tax evasion when she has already been audited?
I went back to her taxes, it was the same amount she owes for either filing as single and MFS.
To everyone her, I'm truly grateful at all the replies. I'm just hoping that the interviewing officer will not ask for a joint sponsor.