Notice: undefined variable: data in c:\xampp\htdocs\latihan2\app\views\home\index.php on line 10

saya sedang belajar php mvc dan baru sampai pada materi model ketika sedang praktek muncul error sesuai dengan judul yaitu Notice: Undefined variable: data in C:\xampp\htdocs\latihan2\app\views\Home\index.php on line 10

kira kira salah nya dmna ya? mohon pencerahan nya thanks sblm nya

controllers/Home.php :

class Home extends Controller
	{

		function Index()
		{
			// $data['mhs'] = $this -> model('index_model') -> getData();
			$data['nama'] = $this -> model('index_model') -> getData();
			$this -> view('templates/header');
			$this -> view('home/index', $data);
			$this -> view('templates/footer');
		}
	}

core/Controller.php :

class Controller
	{

		public function view($view)
		{
			require_once '../app/views/' . $view . '.php';
		}

		public function model($model)
		{
			require_once '../app/model/' . $model . '.php';
			return new $model;
		}
	}

model/index_model.php :

class Index_model
	{

		// private $dbh;
		// private $stmnt;

		// function __construct()
		// {
		// 	$dsn = 'mysql:host=localhost;dbname=phpmvc';

		// 	try {
		// 		$this -> dbh = new PDO($dsn, 'root','');
		// 	} catch (PDOException $error){
		// 		die($error->getMessage());
		// 	}
		// }

		private $nama = 'Mohamad Diki Alfin';
		function getData()
		{
			// $this -> stmnt = $this -> dbh -> prepare('SELECT * FROM mahasiswa');
			// $this -> stmnt -> execute();

			// return $this -> stmnt -> fetchAll(PDO::FETCH_ASSOC);


			return $nama;
		}
	}

views/index.php

<div class="jumbotron">
  <h1 class="display-4">Hello, world!</h1>
  <p class="lead">This is a simple hero unit, a simple jumbotron-style component for calling extra attention to featured content or information.</p>
  <hr class="my-4">
  <p>It uses utility classes for typography and spacing to space content out within the larger container.</p>
  <a class="btn btn-primary btn-lg" href="#" role="button">Learn more</a>
</div>

<?php var_dump($data['nama']); ?>