I would be careful with dairy if you think she might be sensitive to it. Unless she's eating a homemade yogurt you know has alot of viable probiotic cultures in it and not alot of sugar, it could do more harm than good.
Very soft cooked carrots, greenbeans, English peas and squashes (peeled) are veggies that have been safe, in my experience, and will allow her to still get some nutrients. Canned veggies usually have the hard fiber matrix cooked out of them.
Nut butters and avacado can be good sources of healthy fats and calories if she's losing weight. Fish or flax oil will provide omega-3 to reduce inflammation.
The book Listen to Your Gut by Jini Patel Thompson has different levels of diets, based on symptoms and there is a "stop bleeding" diet you may want to investigate.
I'd also consider supplementing her diet with AbsorbPlus, a tasty nutrition drink developed specifically for IBDers.
Diagnosed with ulcerative colitis spring 1999.
Maintenance dose sulfasalazine.
Probiotics, l-glutamine and fish oil caps. George's aloe vera juice. Oregano oil antibiotic, antiviral, antifungal. Long-term remission with only minor blips.