I wouldn't say scary, If the spirit is her mother then I think of it as her coming back to make sure that her daughter is safe and has success in life after failing once at doing so before.

Even putting the fact that horror movies don't scare me anymore aside, I wouldn't call her scary, yet I wouldn't call the ghost cuddly as she was aggressive to anyone other than Daria, even Runt. I'd say that she's somewhere in the middle.