I cannot know what your colleague truly meant, but there are many more explanations than the two that you mentioned. She may simply have offered to do the task

I cannot know what your colleague truly meant, but there are many more explanations than the two that you mentioned. She may simply have offered to do the task out of kindness to you--not out of a belief in her own inferiority. Alternatively, perhaps she thinks you wouldn't pay attention to the task and she would.