I would suggest crafting a thesis that examines these women within the historical context their struggles reflect. You may want to begin with something like this:
Mrs. Mallard and the narrator of "The Yellow Wallpaper" reflect the restrictive limitations common to women in the late 1800s, leading both women to feel imprisoned within their limited freedoms.
I would then devote one body paragraph to each woman, showing how each is imprisoned in her environment and how that leads to feelings of angst and a longing for more freedom than is allowed to her.
Mrs. Mallard has lived in a marriage where her role is to care for her husband. She has fulfilled this role well, and she believes that he has loved her. Her feelings toward him are not the same. When she gains hope of freedom to live for herself, she finally feels more alive than she has in many years. Remember this part:
When she abandoned herself a little whispered word escaped her slightly parted lips. She said it over and over under her breath: "free, free, free!"
She knows that she shouldn't feel delight in this moment of her husband's (mistaken) death, but she doesn't care. She only desires to break free of this role that society has imposed upon her and to decide for herself what is most important each day:
There would be no one to live for her during those coming years; she would live for herself. There would be no powerful will bending hers in that blind persistence with which men and women believe they have a right to impose a private will upon a fellow-creature.
This idea of not having to bend her will in the "blind persistence" which men use to impose their will on their wives could transition nicely into a paragraph examining the frustrations of the narrator in "The Yellow Wallpaper." This narrator's husband is so convinced that he knows how to best care for his wife (keeping her locked away, not allowing her to socialize with others, telling her to remain quiet) that he is blind to her actual health concerns. She is likely suffering from postpartum depression and indicates that she can't be around her own child. In response to this, her husband keeps her locked in a former nursery, complete with bars on the windows, which undoubtedly tortures her soul further. From her barred windows, the narrator can see that which her soul requires for healing—roses, nature, people—but it is all just out of reach, and she is obligated in this society to follow the directives of her misguided (yet confident) husband.
Both women live in an era when women's voices were not heard, and they are thus imprisoned in their marriages. In your essay, you can focus on the ways they both serve their husbands and are almost invisible in their marriages (note that Mrs. Mallard isn't referred to by her own first name for much of the story) and in society to support your thesis.
I hope this helps your planning. Good luck!