Why does my mother resent me so much when i've done nothing but be helpful towards her?

Have you asked her?: She may have very different ideas of what help is in her eyes. She may have resentments that have nothing to do with you directly or she may simply have no idea as to why and may not even know she seems resentful towards you. Can you reasonably let her know how you are feeling? Talk to her before you begin to resent her as well. Wait to do so when you feel the coast is clear emotionally.

Ask your mother?: Right or wrong, it sounds like there's a big difference between your mother's response to you, and your assessment of your activities. What does she tell you about her feelings? Does she hold you responsible for things she's angry about? Is she having difficulties herself? So much here is hard to know -- your overall history and relationship together, etc. Family therapy might help.