Your daughter, is pretty much reflecting her developmental age.
At this age, and other ages, they DO get various night-time 'fears' and of the dark.
My daughter is 7 now... but at that age and younger, she went through that too. And still sometimes does.
Kids, have imaginations and their brain is developing and their sense of night-time unknowns etc.
I remember being that age AND older... and feeling the same way. It is normal. I would get scared too.... by myself... in the dark. AND... the only way I felt 'safe' was sleeping in my parent's room. My sister on the other hand, was different. Each kid is different.
She is a young child.
I really would just offer her comfort and solace. If she needs company/help at night to the bathroom... for me at least, I really don't see it as a 'problem'... because, I see it as a normal part of a child's development....
My daughter, slept in our room too sometimes. We have a floor futon in our room... she can sleep there. NO biggie. My husband also goes outside with a flashlight to 'show' her that it is just the wind making noises... but she is safe etc.
It is something, that occurs in young children... and then they outgrow it. But for a 5 year old, 7 year old, 8 year old... they DO get afraid of the dark/night-time for various reasons.. or even just due to imagination.
And we can't just extinguish, their imaginations.
all the best,
Susan