بسم الله الرحمن الرحيم

Give her a free Holy Qur’an and may start to take to hear what the Holy Qur’an said about Jesus and Mary.
Watch as many videos as you can about Ahmed Deedat and Zakir Naik. Don’t debate with her but these videos will provide you with enough info about Christianity.
There are many videos about the merciless of the Holy Qur’an. Give her a free copy.
Believe me it does take time but keep working in her.