<?php
public function user_login($email, $password) {
        $query = $this->db->get_where('users', ['email' => $email]);
        return $query->row();
}

$current_user = $this->Usermodel->user_login($email, $password);

if (!$current_user) {
    // no such user
} else {
    if ($current_user->password == md5($password) && $current_user->active == 1) {
        // user is validated
    } else if ($current_user->active != 1) {
        // user is not active
    } else {
        // incorrect password
    }
}