Ok, so I thought about the word pray, but the definitions of prayer seems to indicate that you are talking to God, and not just any deceased person, so is there a word for it? It seems that the verb pray can be used to introduce dialogues, but it can only be used to mean that the person praying is praying to God or a person of worship.
For example:
The mother ____ to his deceased son "Be well, son. I hope you will find happiness," as she stared into the sky.