Two cents as well.

1. Your mom's business is very important -- do get it in when asked for bank document. A friend's parents went for the interview and they had a small business too. When VO asked if the business was owned by them, the mom rushed saying "No". Both were declined. They went back again in 2 months and got the visas.

2. August seems to be a high season of visa denial for parents. One of the reasons, as I guess, is too many students apply for visas. I suggest your parents try October or later like Thanksgiving or Christmas.

Hope all goes well for your re-union!