So much good advice has already been given here,
I don't need to add much.
However . . . on the off chance (ahem) that a crucifix would be
inappropriate, and perhaps even more scary than a ghost,
I strongly recommend against putting up a crucifix.
And, if it is not part of your personal belief system
that you have already shared with your daughter,
to call on (pick your theology here) to solve real-world problems,
I don't think following that advice would be a good idea.
I __do__ like the sage burning.
It's a traditional ritual, especially on this continent, for hundreds of years.
It is significantly eaiser, imo, to create a meaningful explanation
to share with your daughter before and as you burn the sage
all around your apartment. You can, if it feels right,
include friendly words to the ghost.
"If you come as a friendly spirit you are welcome here.
But please be aware you are frightening my little daughter.
I do not want her to be frightened any more."
"If you are not a friendly spirit, it is time for you to go somewhere else
where there are no little children who might be frightened by you."
Or whatever feels right to you.
Let your daughter know that you are there for her,
that you won't let anything hurt her.
That you are there to protect her and keep her safe.
Oh! One more thing.
It's probably a good idea to get her vision tested.
If she's seeing double, or having some after-images
whenlooking at lights, she might benefit from
corrective lenses.
Thanks for sharing this story with us.