A fellow walking in a desolate place encounters an old crone. She asks for his help. He says no. So she torments him magically.
Sounds to me as if she really didn't need much help from him, but that's probably not the point of this movie, nor the legend it is based on: Be kind to old ladies, not because it's the right thing to do, but because they'll transport you into a tomb in the middle of a snowstorm.
That doesn't make much sense either, so we'll simply note that this short film by Ferdinand Zecca makes full use of the then-current film grammar, and shows a lively sense of macabre humor, even if someone had no idea of what a cactus looks like.