Urgent, B2 extension still pending after 2 years?

I filed an extension in Feb. 2006 for my mom's B2 visa and she went back to China in July before we heard any decision about her extension case. Her actual return date was a little over 3 months after her 6-month valid length (it was a one year multiple entry visa, and the officer gave her 6 month stay when she entered US), but I was assuming it was legal for her to stay while awaiting for the extension decision.

I would like to invite her to come to visit me this summer. But I don't have any approval or denial letter from USCIS for this case, in fact I just tracked this case online with the case number shown in the receipt letter, which shows it is still pending. Is it possible that somehow the decision was made and somehow we didn't get any letter by mail but the online system has not been updated yet? What should I show to convince the visa officer that my mom was waiting for her B2 extension case before she left US? Would the receipt letter for B2 extension and a printout from USCIS online tracking system (with a current querying date) which shows the case is still pending, plus a proof that my mom left US in July 2006 help? another question is that I am not sure if she can find the original boarding pass, If not, would the stamp showing her entry back to China help? She did submit a photocopy of her I-94 when she left US -- would this show her leaving date in her USCIS record?

Sorry for the long questions. I am worrying a lot about this issue. My father came with my mom last time and went back within a month. He will apply for visa with my mom again this time, but I am afraid that my mom couldn't get her visa due to the complicated extension issue. Any suggestions or information from this forum would be highly appreciated!