Just remove the trailing comma on the last line:
{
"name" : "realtimewebchat",
"version" : "0.0.1",
"private" : "true",
"dependencies" : {
"socket.io" : "0.9.16",
"express" : "3.4.6"
},
"author" : "legit"
}
Edit: You can use this website to check the JSON syntax of your files.