Hi!
Finally we got home. No problems for my husband to come back again to Canada ( uff, thanks GOD!!!! We stressed about it so much!)
The interview took about 15 minutes. I accompanied my husband, but they talked only with him. Only 2 questions asked: to do medicals for dependent children and FBI records explanation. With the first one the declaration was filed already that he is not going to sponsor them, but the officer told that it's the old one (however still on the website). They printed the new form that he signed there. We were confused with the details of Fbi records (he overstayed visa time limit in the US), but figured out that there is a mistake with the code section used, and probably thus there a question was raised. So we are going to gather all the necessary documents and send them ASAP.
Good luck to you!!