As a mother you have the responsibility to protect your child. I know I don't need to tell you that and I'm not insuating that you are not. I merely state it because whether you believe there's something coming into your house or not, your daughter does and it is scaring the s*&t out of her. As a father myself, that would be enough to galvanize me into dynamic action.
Little ones are very sensitive to things that adults have built up resistance to so I think it is very possible that your daughter is truly seeing a spirit entity. Now, whether that's a ghost or some other entity, I don't know, but you should take steps to protect your home and your family.
I don't know what kind of spiritual Path you follow, but whatever it is, you should use it now to create a safe place for yourselves.
Whatever you do to make this happen - be it prayer, ritual, or ceremony - do it from your Heart. Believe in its power and YOUR power. Call on whatever spiritual forces you believe in to aid you (Angels, Allies, Totems... whatever). Like I said, it doesn't matter HOW you do it, just so long as in your Heart, you FEEL the power you are calling on and trust in that power to protect you.
I would do this the next time you are with your daughter and she sees whatever is scaring her. Let her see YOU in YOUR power confront this thing and send it away. That will empower her as well.
See if you can help her to communicate what she is seeing. It's hard with the very little ones whose language hasn't developed much yet but there are other ways. Page through magazines and see if she can point out pictures of things that are like what she sees. See if she can draw a picture of what she sees (probably not likely at two, but you don't know until you try...) Think outside the box. Take every opportunity to show her that you believe her and that you are there to help and protect her. That will empower her too.
Let her be your guide. Watch her when she reacts to whatever it is. When she gets more scared, you get more aggressive. When she gets more aggressive, back off and let her do her thing. Protect and empower; that should be your motto and Path in this.