I am sending huge sympathies, and hugs...this is so very sad for you all.
how about doing a memory box with her of her daddy. help her write her best memories of him, and also her fears.
put in anything that she finds special....anything. it may be nothing of huge importance to anyone else,it may even be a leaf that her collected with her, or a pebble from the beach.
pictures too....ones of her with him, and also ones she has drawn of him or for him.
maybe also some item of his clothing....and his favourite song.
anything that can go in there will be something that will help her stay connected, and it will also be a place for her to go when she needs ot feel close.
i hope this helps.
xxx