Is Billy Back?

I haven't written anything recently because nothing has happened, I was really starting to think they had left. But apparently at least one of them remains in the house. My sister's friend Billy.

Something happened a few days ago. My mom had finished dressing my sister, but she had to go do something and she asked me to comb her hair, so I said yes. As I was doing this my sister and I were talking about her kindergarten and then she just stopped talking. And she was staring at the door. And then she said:

"Billy, what are you doing here?"

And then I asked her why she was saying that and she said that Billy was back.

I didn't sleep that night. I couldn't get it of my mind, was Billy really back? Did he bring the others with him? And then I heard someone open my parent's bedroom door, walk down the hall and go down the stairs. I knew it had been my parent's door, because it squeaks a lot when you open it. I thought it was my mom or my dad. I decided I should go downstairs too. I was really thirsty and someone was already down there with the lights on.

I went out of my room and to my surprise the lights downstairs weren't on; the hall light was of too. I opened my parent's door and they were both asleep. I ran to my room and just lay there totally petrified, I know what I heard. I couldn't sleep for the rest of the night, not after that. I kept hearing weird noises for the rest of the night.

Sometimes it was knocking on wood, only not on any wood item in my room. I knocked on every one of them and I couldn't recreate the knocking. Sometimes it sounded like if people were having a conversation in the hallway, but I don't know what they said.

Sometimes it was a mechanical noise, but I really couldn't tell you what it was. I got so frustrated I ended up yelling at the top of my lungs:

SHUT UP! And they did.

I fell asleep after that, it was like three o'clock. The next day we had to go run errands in the city, we live in the country but it's only like a half an hour drive. I couldn't find the lip gloss I wanted to wear that day. My mom was rushing me, so I just left. \

When we came back I found the lip gloss in my dresser, it was sitting on top of it were I would have seen it. I swear it wasn't there before!

How do I get rid of Billy and company, for good!?