Miriam faces her death with a "sensation of abundant peace "Explain?

Mariam is happy that Laila, Aziza, and Zalmai are safe with Tariq. She has felt the love that she had always longed for from Aziza and Laila. She feels her life is a small sacrifice to pay for their happiness. I think that, on some level, she had to feel a little satisfaction by killing Rasheed.