I need to compare a movie to the play Trifles. I just can't think of a movie. I saw someone compared it to A Doll's House, but I've never watched...

From the comparison that you provide, the assignment asks that your compare the play Trifles with a movie that has the subject matter of subjugated women. The reason why this is the rationale of the assignment is because the play A Doll's House has nothing to do with the play Trifles, except for the use of the topic of women being marginalized, or pushed down, by a male-dominated society. In this case, society is microcosmically represented in the marriage dyad, where the male dominates and subjugates the female.

If what you need is a movie,like your question states, and not another play, you may want to watch Sleeping with the Enemy with Julia Roberts, or Enough with Jennifer Lopez.

These two movies are about the effects of domestic violence on battered women. They also explore issues such as the "battered woman syndrome", "post traumatic stress disorder in domestic violence (DV) victims", and "women who snap". 

In Sleeping with the Enemy  the main character comes into a manipulative marriage as a willing participant, as she does not know any better. The husband uses her feebleness and naiveté to push her down further by not allowing her to engage in a number of activities. In the end she manages to escape, only to have him chase her again, until she no longer can play the "cat and mouse" game; one of them definitely needs to go.

In Enough, the same topic is used, except the main character has a child who she has to defend, as well. In the same way, the main characters snap at the prospect of going back into the submission of abusive men. In both movies, the men meet their ends at the hands of the women that they abused. 

When conducting a search of movies depicting battered women, it is surprising to find out that modern movies seem to shy away from the topic. Instead, they are trying to instill stronger, more initiator-type female leads into the overall psyche of worldwide audiences. The idea that a woman enters a relationship to be mistreated is something Hollywood cannot glamorize, therefore, it is hard to get those movies to hit the silver screen successfully.

Regardless, think how Minnie Wright is also a victim of a man who uses her feeble nature, her naiveté and her kindness to his complete advantage. Rather than bringing out the best out of two people, a chaotic and toxic DV relationship will plunge the couple down altogether, with one using the other as an scapegoat for all sorts of abusive behaviors. Poor Minnie was no different than a punching bag where John would release his anxiety, anger, and violent emotions in a dangerous way. This is why, when he kills the canary, he actually kills the very last nerve standing in Minnie's soul. And, she lost it.