She needs more blood work done. T3, rT3 and TPO are big factors in this equation. I am a nutritionist and have been battling this personally for over a year now. If her T3 is high, her liver is not converting T3 to T4, thus indicating a liver cleanse would be most beneficial. I would tell her the first this she needs to do is determine if it's really Hashimoto's. If so, gluten and dairy must be completely eliminated, along with most grains. And, by eliminated, I mean completely eliminated! It will not do her any good whatsoever to have it here and there. For people with gluten insensitivity, which is most hashimoto patients, asking them if they eat gluten with a response of "I think so, maybe occasionally", is like asking is you're pregnant - it's either yes or no, NOTHING in between! One bite of gluten will set you back 6 months with the inflammatory response in your body.
Foods with high levels of lectins must be avoided, this would be nightshades mostly. Cleanse the liver with dandelion root and milk thistle. Stay away from iodine. Have CRP (C Reactive Protein) measured for inflammation levels. If high, eliminate peanuts and almonds, among other inflammatory foods.
Too much to cover here. But that's enough to get you started. Good luck!