The very minimum you need for AjaxHelper
NuGet Package Microsoft jQuery Unobtrusive Ajax 3.1.2
> Install-Package Microsoft.jQuery.Unobtrusive.Ajax -Version 3.1.2
Now include the scripts
<script src="https://stackoverflow.com/questions/23895918/~/jquery-1.11.0.js"></script>
<script src="~/jquery.unobtrusive-ajax.js"></script>
Go ahead and get the latest version if available. I specified v3.1.2 to demonstrate that the AjaxHelper worked for at least this particular version at a particular time.