$conn = new mysqli('localhost','user','password','db');

$sql = "SELECT Status FROM Users WHERE Username = '".$_GET["username"]."'
AND Password = '".$_GET["password"]."'";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
// This is where it is giving the error
        echo $row['Status'] ;
    }
} else {
    echo "0 results";
}
$conn->close();