being inside the church is to seek spiritual guidance and uplifting ones spirituality in times of hardship, and/or you are in need of guidance.
a person with blonde hair symbolizes glamour and enjoying life, the dog face i'm unsure of, what type of dog was it? or what colour? a dog represents loyalty, but if it was vicious then it means controlling situations.
a priest is spiritual guidance, but since it's her grandfather, a grandfather is protection and wisdom. exorcism is a step towards goals.
blue is wisdom and a dress is feminine, so feminine wisdom.
the whole bad feelings and the deja'vu thing i'm not sure what you should tell her. as a kid i went through the same sort of things. i remember having this reoccurring dream where i jumped off the second story of my grandparents house and floated down into the dining room [there's an opening in the second story that you can look down into the dining room] for years whenever i entered the dining room from the one doorway i go so light headed i had to lean against the wall for balance. it just went away one day. these things never scared me, my grandmother [other side of the family] told me the woman on that side were psychic through our dreams, and i took comfort in that, i knew what was going on.
what you should do, depending on her age, is try and get her into meditation, chakra work, it will help her control it somewhat. look into herbal teas for her stomach and nerves, but you should find someone who can help teach her so they won't run wild.