I think it should be
echo $db = mysqli_select_db($dbSelect) or die('Database Not Selected');
you connected to the database using mysqli_connect so try selecting using mysqli_select_db too. and better still specify the database your and connecting to in the mysqli_select_db if you have more than one connected database
echo $db = mysqli_select_db($dbc, $dbSelect) or die('Database Not Selected');
and to remove the database selection part just use
echo $query = "INSERT INTO enquiryform.gcmas (Name, EmailID, Phone, Message) VALUES ('$name', '$email', '$phone', '$message');";
while you remove the mysql_select_db part