Hopefully some one else will chime in with some links. Unfortunately I do not have them saved on the computer I'm currently on and won't have access to them until Monday (where I expect to be really busy ) But there are two websites (to include this one) where you can research some information that might be helpful.
The biggest thing that I think is important for you to understand is that dogs process chemicals/hormones differently than people do. Ever been in a fist fight or a serious argument? Know how you feel immediately after? Serious adrenaline rush-right? (not necessarily good, but still a rush) For dogs-that feeling can last for up to two weeks. It takes them much longer to process those chemicals/hormones. You should keep Marley separate from all of your animals for now. Give her some time to chill out, calm down and readjust. Life has changed for her. Eloise is gone. She's amped up and the cats are more aggravating to her. It may be that she can never safely be around the kittens again. It may be that she simply needs this time to calm down. For a Pit Bull type dog to have aggression towards other dogs or animals is not uncommon. It's a very well know trait of the breed, and it is an acceptable trait-there is nothing wrong with your girl.
I don't know what your set up is when you're away from home but all of the animals need to be separated. This helps to ensure the most safety. Is Marley crate trained?
If it were me and I was concerned about Marley guarding the room...I'd simply change rooms for her.
Best of luck to you! You've been approved to post, and you may want to repost this either in general or training/behavior as the the intro section doesn't really get a lot of traffic.