The correct answer is:
Take heed, you yet may trip and fall.
In Christina RossettiĀ“s poem, Helen Grey is warned about her unpleasantness, claiming that because of it she will be alone and unhappy. Since men think she is beautiful but her personality is not, they will find her unattractive. Therefore, if Helen Grey does not change her ways, no man will try to help her if she falls.