Most colleges don't do graduation ceremony in December. They do in May for December graduates. Your university having convocation in December or May? 

40 parents applying in a day wow. This is not a school starting season so may be all are parents.

I think they don't want tourist from Nepal during christmas as they don't want to overcrowd NY

One thing what  Nepali American citizens(sons and daughters) do is as soon as sons and daughters get citizenship, they apply GC to their parents so that they can get senior citizen bhatta for their parents from American government which is actually taxpayers money. That is why I guess the consulars are angry with old people.(my guess)