As a mother who recently lost her daughter, I would suggest to just be there. Books, writing poems, all of that stuff really isn’t helpful at this point. Just be present. No judgement, be supportive. Be loving. Don’t tell her to get over it, or it’s time to move on, or to get a therapist. Just be there. Clean her house, cook a meal, wash her laundry, bring her flowers. Bring her a coffee. Give her lots of hugs. All of that means the world to us. Books mean nothing. Sorry, just talking from my own experience and what I wish my own people would do for me.

As you can see, there are a lot of busy people around here. I am sure that someone will be here to help. I would thinkif you went online, you would be able to find several self help sites. I realize you want a recommendation. Good luck

here is how to help a friend going through a loss:
https://www.helpguide.org/articles/grief/helpin...

Do not rush her. Allow her to feel everything she needs to. Be there, even if that means sitting with her in silence.
Here is an article that helps understand what she is going through and how you can be there for her https://www.verywellmind.com/five-stages-of-grief-(Phone number can only be seen by the question and answer creators)

Tell sorry for her loss...
Be there for her if she wants to talk , cry whatever just be around