I'm afraid the mystery of the Number 10 is still at large! Isn't it strange, that out of the whole conversation, that was the only thing you could remember.
It is one of the most enlightening aspects of reincarnation to find out that your children have a soul much older than yours. Some people just find it hard to accept that their children may very well be more wise and much more fearless in life, as they have been reincarnated so many times before. Sometimes they can say the most profound things, and sometimes they can even help us along the way, just how your daughter helped you so many times in the past.
I understand now why you felt that your daughter wasn't scared, while she was 'alone' in the room. Even in your dream, your subconscious mind realises that your daughter is not one to be frightened very easily, more specifically when concerning spiritual things 'from the other side'. At the moment when you were leaving the room and realised there was a ghost in there with your daughter, these deeply embedded feelings were very much present. Her tolerance for ghosts and understanding of things you may not necessarily know about is the very reason for why you feel your daughter is a much more stronger person.
At the surface your dream seems quite eerie, however once you really think about it, it actually seems quite beautiful.
I don't believe this dream was sent to you in order to scare you in any way, but more so to the fact, to incite a feeling that answers a question every mother thinks about before she sleeps at night; Are my children doing ok?
Especially when they leave home, parents can get quite stressed over their children. These fears do play into your subconscious mind and sometimes come to surface at the most unexpected times.
Most mothers would feel completely terrified if they learnt a ghost was in the same room as their child. But you weren't. Your daughter's bravery and ability to handle such situations, was such a sure thing that you kept walking. You didn't stop and run back to check on her... you kept walking.
Sometimes dreams can be quite scary in order to drive home a message. It doesn't necessarily mean that your house is haunted, or there are ghosts playing Beethoven's Moonlight Sonata No.14 up in your child's bedroom
I can only contemplate as to what that message is. I do believe it goes something along the lines; Even if life presents a situation that you may believe is quite scary, deep down inside you already know that your daughter is able to take care of herself. This should be quite warming, as I know a few people who couldn't say the same thing for their daughters...
To answer your first question about the attempted robbery;
I don't believe this is connected on the surface, I do however feel it may be connected by the underlying emotions much described by the message of your dream.
I do not believe your niece is outwardly connected. I was however asking who played the piano in order to maybe try and establish a family member who had a friendship with your daughter. I am however quite convinced your niece isn't connected, due to the fact that it was your daughter in the bed, and not your niece. This does however establish why you were hearing a piano, and maybe not a violin... lol
There is this personalisation aspect to pianos, especially around young girls in your family that seem to worry you? This may very well have triggered your dream in the first place.
I hope that helps