Reasons for extension denial ? Urgent

[renu_v]

Hello
What are the general reasons for denying an extension?
am going to apply for extension for my parents for urgent reasons.

Thanks for helping

[renu_v]

So, what reason should I give for extension now? I am due in Jan end.
Should they go back now and come back in 3 months again? That would also be a risk , right?

[peace]

How much time have they spent here so far?