What must the questioner's niece do to make up for the Ramadan fasting she missed, and must she fast two days for each day and feed a poor person?

"It is not necessary to fast two days for each day that was delayed in being made up. If the delay was due to a valid excuse, then she is not required to do anything except make up the fast. If it was without a valid excuse, then she must pay an expiation (fidyah) by feeding one poor person for each day, unless she was unaware of the impermissibility of the delay, in which case she is not required to pay the expiation."