If she is rejecting Gods' Word, then she is rejecting Jesus Christ. You are not alone with family members not being saved, you probably may already know that. In my earthly family out of all my (aunts, uncles, cousins, brothers, mom, dad, grandparents, step-dad) I don't think any of them are saved and have truely repented from their sin my grandma even got angry with me and told me something like don't preach to my cousin. My family can curse Gods' name and then laugh afterwards, it is sad and terrible. So I would suggest or agree with others on here to take it to God in prayer. Pray for the conviction of the Holy Ghost to come upon her. Perhaps you might want to fast and believe God to give you a Spirit of prayer that the Spirit of God may groan through you and you can prevail in prayer on her behalf for the power of God to come all over her. You should seek Gods' wisdom as to how He wants you to go about it. It can be tough bearing the burdens of your family members eternal salvation, so if we are bearing a burden that is not ours to bear perhaps we should ask God and continue to ask God for the faith and grace to leave that burden at the cross and trust Christ with the outcome of our loved one. Also He won't take away free-will either, I just hope even a small portion of my family will be saved; they are deceived, may God open there eyes and the eyes of your mother. There is nothing to hard for God, He is mighty! So just ask Him for the grace to trust Him with your mothers' eternal destiny and try and enter into some deep intercession on her behalf.