As your dad's application is in the Background Check stage, sending another CSE/email to the visa office won't help to expedite the processingNo no they returned in August 2017. They went to Canada in Jan 2017 and came back in August 2017 as I have got them one month extension.Their visa was valid till December 2017. But due to my wedding we all were in India in December 2017. So now as there visa was expired so I applied for their visa in Jan 2018.
Hopefully they will be issued TRVs soon