use node field handler as a parent for node-related fields

  $data['feeds_source']['feed_nid'] = array(
    'title' => 'Feed node id',
    'help' => 'Contains the node id of a feed node if the feed\'s configuration is attached to a content type, otherwise contains 0.',
    'field' => array(
      'handler' => 'views_handler_field_numeric',
      'click sortable' => TRUE,
    ),

use the views_handler_field_node handler to inherit options to link to the node.