Yes certainly “Om Namaha Shivaye” will certainly help her. She can do Monday fast as well. You can read about Monday fast procedure on this website.
However sometimes we need to give much stronger remedies and specially when the Saturn is disturbing her as I can see from her horoscope. For Mental peace and positive through strengthening of Moon is very important. I suggest that you make her wear a Pearl in Silver minimum 8 – 10 Ratti and above. Good quality Pearl which is white in color and not Cream. Should touch the skin for benefits.