I think it may be too soon really for her to consider this, she will be in a raw, vulnerable state.
Although time does heal, losing someone close is never something that you completely get over, you just learn to accept and deal with it in every day life. For the time being, I would avoid trying to offer her the thoughts and ideas of a published author, and just let her deal with and take comfort from her own ideology of where her dad may be now. That goes for spiritualists also. If she really is intent on going to one for her own piece of mind, just let her but encourage her to wait a while.
Feeding her vulnerability may do more harm than good.