(her)

 "Your mother died to save you. If there is one thing Voldemort cannot understand, it is love. Love as powerful as your mother's for you leaves it's own mark. To have been loved so deeply, even though the person who loved us is gone, will give us some protection forever."
- J.K. Rowling, Harry Potter and the Sorcerer's Stone
Mom is just not a relation but a feeling. A strong compassionate feeling that showers unconditional love. The love that she hold for us is indeed our biggest shield for all the hard and tough times. <3