This is a tough one. Usually children do not realize that death is a reality until they are school age between the ages of 6-9. So, my first question would be is there anything that has happened in your child's or family's life that has put death in the forefront for her? At 5 years, she is dealing with the separation aspect and not the finality of death. Children 3-5 years are still in the magical thinking period and believe that magic still happens. That is why they talk through their stuffed animals. And they believe death is reversible. When the school age child approaches the concept of death, the child understands that it is permanent separation. They see it usually as dark and sometimes as evil.
Either your daughter is very advanced emotionally for her age or she has been exposed to death as a reality and this has frightened her. The one thing all children need is to know that she is safe within her family and she is very loved. As the child moves into school years, they think more concretely and can begin to understand the role of religion in the life/death cycle. IF you are involved in a church, perhaps the minister can talk with you and her.
I worked with children who had cancer for years and dealt with this issue with all age children. Assurance of love and security is the number one thing to give her.
Good luck. Children are wonderfully made!
A. Pryor