exports.handler = function(event, context, callback) {
    callback(null, {
    statusCode: 200,
    body: "Hello, World" + event.queryStringParameters['email']
    });
}

exports.handler = function(event, context, callback) {
    callback(null, {
    statusCode: 200,
    body: "Hello, " + event.queryStringParameters['email']
    });
}

Update hello.js