how do you know it's a negative spirit? spirits sometimes just want to be noticed, and the only way to get attention is to move objects. this doesn't mean it's evil, it's just lonely. some spirits dwell somewhere to protect it, so your friend shouldn't jump to the conclusion it's a negative spirit because it moved something.
you should gather more evidence before claiming it's a spirit, someone could be playing a prank on her. changes in temperature, the feeling of being watched, noises, these things coupled with objects moving can account for a spirit.
spirits don't always remain where they died, some are attached to the house because of a long painful experience, but spirits can come and go as they please for the most part. this spirit could of been wandering, felt her home was inviting, and decided to stay for whatever reason. that's happened to me, a spirit just randomly came into my room one night while i was reading and i invited him to stay. other spirits attach themselves to a person or object for whatever reason. your friend could of bumped into a spirit while she was out and it followed her home, or she could of bought an object the spirit was fond of in life.
if i were your friend, i would try communicating with the spirit without a Ouija Board to see what it wants. if she feels concerned a protection spell is a good idea, and if she chooses to kick the spirit out, ask it nicely to please leave because it's her house and the spirit is a guest. if the spirit doesn't go, get some sage smudge and burn it, go into every room and waft the smoke though every inch, chanting how you want the space cleansed. [find one online or make one up] be sure the windows and doors are open so it can leave, but close each one as you leave a room. finally, cast a protection spell on your house to prevent it from returning. you might have to redo this a few times until she feels safe. though you should get in the habit of a semi-annual cleansing/protection.