Form 221(g) IV pending submission of 2016 tax return

[bisdakako 0]

My daughter in the Philippines just had her IV interview and was asked for my husband's (USC petitioner) 2016 tax return even though we submitted 2016 W-2's as well as tax returns for 2015, 2014, 2013 as well as employment certificates/letters and paystubs. She was given the form 221(g) and told to send the document they asked for. They also kept her passport. 

 

When I looked up what the form 221(g) was for, I was nervous because it said it basically is a temporary refusal or put under "administrative processing." What should we expect next? How long does this Administrative Processing take after we send over the required document? Is there anything else we can do to speed up the process? Anyone who went through this, please shed some light into this matter?. We are so confused and worried!