I like the response from Rhonda. She could have sleep apnea which has been causing her to wake up. Maybe the startle response to not breathing is scaring her.
I was also thinking that she may be too hot. My 3 year old daughter used to sleep on a matress cover that had a plastic lining. Every time I checked her on her she would be very sweaty, so I found a Simmons waterproof mattress cover that has a waterproof fabric lining. She seems a lot cooler, so though the mattress cover was expensive, she seems more comfortable.
I know that when I get too hot while sleeping I have terrible nightmares. If I'm really hot I wake up during REM sleep, when my body is paralyzed. Talk about the most frightening experience! You can't even scream! So if you haven't already done so, try taking off a couple of blankets and take your daughter out of the footed sleeper. Maybe she doesn't like the feel of pajamas on her legs; try shory pajamas or a nightgown. (I refused to sleep in pajamas as a baby).
I keep a fan running in my daughter's room as white noice and ventilation. If jets fly over your house, the white noise really masks the jet noise.
I was a terrible sleeper as a preschooler, and I still have trouble sleeping by myself. I had night terrors as a child because I was too tired when I went to bed. I was also petrified of ghosts because we lived in an old house and my siblings loved to play up that fear.
I was determined that my daughter would be a good sleeper, and knock on wood, she is. I use black-out curtains and white noise, so my daughter sleeps in a re-created womb. She complains if the room is too bright when she needs to go to sleep She still has her moments, like when she loses her lovey in the covers or she is coughing too much with a cold. But once I find her lovey or get her a drink of water, she goes right back to sleep.
As to monsters and ghosts, you could tell you daughter monsters only live on Sesame Street, or spray scented water to chase them away. Or you could say that your house is too new to have ghosts or monsters, or that you paid too much money for it to have such manifestations. You could even try hanging a Dream Catcher over her bed. I've heard that works.
I hope something helps.