If the delay(rescheduling) is well announced in media, then the option which you have selected 'Delay more than 3 hours' will not be valid. Instead, you could have filed the TDR stating that the passengers have not traveled and you could have got some refund.
Since, its tatkal ticket, I doubt whether anyone would get the refund in these cases.
Leaving the tatkal and other charges, I guess you are eligible for 50% of the base fare.