No, a "spirit" does not need anyone else to be able to move around. They are around us all the time. They would need someone who can communicate with them if they wanted to get a message to you but a spirit would never give you a message that would upset you or give it to you if you were not in the right frame of mind to accept it. So if you don't like what this lady is doing, then tell her. If she is using her abilities wisely and as she should she will not force it upon you, but respect your wishes.