It would be interesting to write a research paper in which Darwin's theory of evolution and the so-called "Woman Question" would be put into perspective. Here on Enotes there is information about that specific bracket of Darwin's theory which was inevitably developed under the social statutes of the time, where women were still subservient individuals. So, by exploring the expectations that were placed upon women in Louise's time we can connect whether they were completely socially-made, or if the advent of scientific research of her time,nay, Darwin's time, influenced in anyway the manner in which women were looked upon.
You may wish to examine the influence of the femme covert laws (historical) upon the life of Louise Mallard. For, it is the resulting repression of these laws that effects the "heart condition" of Mrs. Mallard that is central to hour of her life which the reader views.
A good theme for almost any paper on a good work of literature results from asking how the particular phrasing of the story is effective. In other words, why is "The Story of an Hour" worth reading and re-reading and re-reading rather than some other story about a person who feels oppressed? After all, if Chopin had merely wanted to express her ideas about a particular topic, she could much more easily have written an essay. Why did she choose to write a story, and how is the story effective or compelling, especially in its individual word choices?
One good way to analyze the style of a work is to imagine how a writer could have written differently. Why did the writer choose the words she did rather than some other words that mean roughly the same thing? For instance, consider this sentence from Chopin's story:
Now her bosom rose and fell tumultously.
Why is this a better sentence than the following alternative?
At this point in time, her chest began to heave up and down.
If you do this kind of comparison and contrast exercise frequently enough, you will have plenty of evidence to make a good argument that Chopin is not just a writer with certain ideas but also a writer with real skill in writing stories in which those ideas are part of the story's interest, but not the main part.
I see the theme of equality or lack of it. She would be happy if he considered treating her as an equal.
How about disappointment? Seems like she's been disappointed with her marriage for a long time, and when things finally change, in walks her biggest disappointment: her not-dead husband.
The main theme deals with a woman having her own identity apart from her husband and having some sense of herself. At first, Mrs. Mallard doesn't know what is happening after she goes upstairs to think about her life, but soon the word "free" begins to form in her mind and on her lips. She now begins to look forward to the future, when only yesterday, she'd wished she would die at a young age. She thinks about how wonderful her life can be without her husband, how she can now live for her and no one else. After experiencing this freedom for such a short time, she collapses and dies when she sees her husband is alive, unable to accept that she had her freedom for such a short time.