Reread Ally G's post. She is right on.
I know parents who chose not to make movies a battle they fought with exes, but I think it has to be done movie by movie.
Both the ones you describe are not at all appropriate.
If you have an easygoing relationship, is it easygoing enough that your hubby (not you, this is HIS time to deal with things as it's his ex) can talk to them about it? He should not be accusatory; they may have gone to see these things with little real idea of what they were about (believe me, some adults pay NO attention to ratings or reviews and just haul kids along to what the adults want to see, period). In fact I bet that's what's going on -- ex and her husband are just taking kid along on their adult movie night. See if your husband can talk to them about that factor and whether their time with her can be rearranged so they are not including her in grownup movie time. Also, it would help if your stepdaughter had said things to you about how she was upset by/lost sleep over/was grossed out by such things.....Can't make it up if she didn't say it but has she seemed upset by these movies?
Maybe you and they can agree that both families will abide by taking her to films that are only PG or below, maybe PG-13 though that depends on the film.
As for the person who posted that "Zero Dark Thirty" is based on real events so she'd know about them if she watched the news, so what's the big deal -- Knowning a story is true is NOT the same as actually watching depictions of torture on a huge screen before your eyes. If the other parents try to use that excuse -- wow, they are not thinking about her mind and heart.