Hmmmm....break the doll. In fact, break anything that does not produce light. If you notice, most things that are not light producing sources are personal items - look at the write up. The doll belonged to the girl, it is her possession. The dress was someones possession, the lawnmower was someones possession - the power tools, the CD, etc.

I mean, looking at it this way the demon, if that is what it is, is possessing us. I'd expect such a subtle hint from our esteemed host.