ok, I'll say it, I doubt theres anything there. A random firealarm kept going off, they might have needed to change the battery or just disconnect it altogether but either way I doubt it was the cause of her only getting an hour sleep. They had the whole family camped out in the one bedroom, that alone could cause lack of sleep.
Not only that but how do we know that bruise is even from a ghost, they dont go into much detail about anything other than they came home and heard some noise so they went running to a priest... Yeah
I'm sure thats what anyone would do if they heard noises and walking around in their place when they got home instead of calling the cops just in case someone had broken in. The kids 13 and a boy, they bruise a lot, at least my friends and I did and the bruise might not even show for a day. Kids run into stuff, rough house it doesn't mean that the bruise had anything to do with anything other than something totaly normal...
Now to get on the real sinister side, what if he is being smacked around but its not by any ghost and their just telling him to make up some ghost story?
I'll give the priest some slack, not much he could do really. They arent spirit exorsizing rambo's that just rush in and start blasting away, it looks like he did the right thing. He went to the place and did some prayers, obviously he got no reaction which means he couldn't go farther because for a priest if prayers dont stir somethin up that shoulndt be there then its probably not there...
Also the landlord said this was the first time its happened which means there were other tennents living there, it would be interesting to find them for interview...