A possible thesis might focus on addressing, from Louise Mallard's perspective, the question of whether the price of personal freedom is worth the gain of love and home. If you think for a moment about Austen's Pride and Prejudice, you might recall that Charlotte thought the price (Mr. Collins) was worth the gain (a home of her own). Mrs. Mallard's death seems to indicate that in her perspective, the loss was not worth the gain, but this speculation would need to be supported or contradicted by other elements of the text.
A good thesis statement for this story might discuss the fact that the original title of the story was "The Dream of an Hour." A good paper could be written discussing all the various ways and senses in which Louise's experience might be described as a dream in positive and/or negative senses of that term. You might also want to consider why the title of the story was changed. Is one title better than the other? Is one title more revealing than the other? Does one title work better at creating suspense? How do the different titles affect our understanding of Louise's character? These are some possible questions you might want to consider.
What about examining how much one's psyche affects one's health? Here is a woman of spirit who is being caged in the patriarchal society of Victorian times. She is so repressed that she is described as having "a heart trouble"; yet, the Victorian doctors who do not admit psychological causes cannot define this trouble in definitive physical terms, so they use this nebulous phrase. Mrs. Mallard demonstrates symptoms of heart problems, but when she realizes a new-found freedom, she feels great, "a goddess of Victory." It is only when her hopes and desire of individual freedom are again crushed by the appearance of her husband that Louise Mallard dies. Again, the crass doctors call it "a joy that kills."
This wonderful short story clearly deals with issues of oppression and suppression of women in patriarchal societies. It makes it clear that although Mr. Mallard did love her and was not cruel in any way, still, the expectations that society placed on wives at the time were crushing. Thus your thesis statement needs to focus on some of these elements, exploring the role of women in the time and how this story exposes the place society allotted to women.
"The Story of an Hour" deals with the issues of identity and the role of women in marriage. Mrs. Mallard's identity has always been as a wife, not as a person. When she first discovers her husband is dead, she grieves. When she is alone, however, she begins to realize she will no longer have to be subjected to her husband's will. After she speaks the words, "free, free, free", she realizes she is now in control of her life and that she will never have to do what is expected of her, according to her husband's wishes and society's expectations. She looks forward to her future where she can do as she pleases when she pleases. For one hour, Mrs. Mallard is a person who is on a path to self-discovery. When her husband walks in the door, she is unable to accept the loss of her freedom and dies. She cannot go back to what her life was before, a life of being just a wife.
A good thesis statement for The Story of an Hour would be that the story unveils the inner psychological strains of women whom were subdued and underrated by unbearable social expectations upon marriage.
In this story, a woman is told that her husband has passed away. It is interesting to see how this became a ticket to her freedom, not so much physical, nor social, but psychological. Many women were put into that predicament way back when marriage was an expectation, if not an obligation. Many young women were expected to be ready to be nurturers, mothers, supporters, heads of households, and to completely give up their personas in order to become a shadow of their husbands.
Yet, women were no different genetically then as they are now: We all have had wants and needs since the beginnings of time. Quenching the ideas, hopes, dreams, personalities, and wishes of any human being will meet with the horrors of repression and depression.
The woman in the story of an hour was definitely both: repressed and depressed. And, as she finally saw a way out, learning that her husband was not dead after all made her collapse and die. It was that bad.