Why do some get their miracle from God and others don't?

I just finished watching Miracles from Heaven.  It was such a wonderful movie.  If you haven't seen it the movie is about a little girl from Texas who has a disease that causes her intestines to not digest food. Her mom gets her an appointment with a doctor at Boston Children's Hospital who is an authority her condition but he doesn't give the family any hope.   There is no cure for it only experimental treatments.  She continues to get sicker and sicker with no hope for the future. She tells her mom she is ready to die because she is in so much pain and knows she isn't going to get better.  Once home she climbs an old hollowed out tree with her sister and falls down the middle of it. She is knocked out and it takes the fire department over 3 hours to get her out. Because the tree is completely hollow they can't cut the it down for fear it will collapse and crush her.  For whatever reason the fall healed her. She came out of the fall with only a few cuts and scrapes and her digestive system just started working again.  She told her parents she talked to God and told him she didn't want to go back but He told her she needed to and that she would be okay.  
I tell you all this with the big question "Why did her miracle get answered?"  When Dad was in the hospital he had so many people praying for him.  We all prayed for a miracle, that he would be healed and come home but that didn't happen. I remember sitting by his bed talking to him and praying over him.  I remember Royette doing the same as well as the pastor from their church.  I know everyone at her church was praying the same thing, that he would recover from the complications from surgery.  So why didn't God grant us our miracle?  I wish I knew the answer to that. I wish I could understand God's plan for us and what we are suppose to learn from Dad's passing.  We hear, when there is a death in the family or someone is injured, that God is in control and has a plan for everything.....WOW is that hard to grasp. As I sit here typing this blog on Christmas eve I keep thinking about the miracle that is Jesus Christ. God gave us his only Son as a sacrifice for our sins.  I know that should comfort me. I know my dad is in heaven and that he isn't feeling any more pain or sadness but that doesn't make me miss him any less.  I still get angry. Angry at the doctors thinking they missed something.  Angry at myself for maybe not praying enough.  Anger and sadness that I won't ever talk to him again.  Angry at God that we didn't get our miracle.