Check out for annexure 1 in this circular. All FAQ’s by NSE.
As per the exchange all positions getting exercised will be considered as delivery trade on that date. So it is like buying/selling stocks in your demat. Online brokers will hence need you to have full money or full stock on the expiry date. Offline brokers might give you time till the next trading day.
But here is the thing, the risks of client defaulting and hence a huge penalty on broker is quite high in this. Therefore, most brokers might be asking for full money/stock 2 days prior.