I agree with the above poster. I am 26 1/2 years old and I don't like to be alone. One other thing you might want to try is get her a teddy bear or other stuffed animal. You can tell her something like this is a safety stuffed animal and he has come to take care of you and rid you of all the scary things in your life. It worked for me when I was her age.
May I ask why he was hiding in the house and if he still is around and in your lives ?
This is called anxiety. Your daughter is now nine years old - old enough for therapy. Perhaps it is time to discuss this with your family doctor. If he/she is unable to help you (and I doubt if he/she can), then ask for a referral to a mental health specialist with experience in anxiety disorders. The best therapy for anxiety is CBT - cognitive behavioural therapy - this might be the place to start. Doing nothing is not working, and without help, it will affect her for the rest of her life. But, anxiety is very common and highly treatable. All the best ....
How sad to hear this. Although this has been going on for a few years now, she is only 9 and if she experienced a tramatic event as you said, you are going to have to give it time.
I wonder if there is anyone outside the family that you trust that could try to work with her o this? Sometimes a fresh perspective can help a lot. I may send you a pm later with some thoughts.