Whenever problems and heartaches come into our lives we have a choice to make (even if we don't realize it). The choice is simply this: Will I turn to God with this problem, or will I turn away from Him?
I'm sorry your mother apparently allowed her problems to overwhelm her, instead of turning them over to God and seeking His comfort and strength. I don't condemn her for this; it's easy to do when life turns against us. But I hope you will learn from her experience and turn to God when problems and heartaches arise—as they will. The Bible reminds us that "God is our refuge and strength, an ever-present help in trouble" (Psalm 46:1).
Only God knows our hearts, of course—but If your mother had truly accepted Christ and trusted Him for her salvation, then you can be confident that she is now in heaven with Jesus forever. Remember: We are never saved because of our own goodness; no matter how good we are, we will never be good enough. We are only saved because of Christ and what He did for us on the cross.
This is true of us—and it was true for your mother, as well. No, she wasn't perfect, and neither are we. But all our sins were placed on Christ, and He shed His blood to save us. Your mother's hope was in Him, and I pray yours is, as well.