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by

Try 

function crudindex(){
   add_options_page('Crud Dashboard', 'Crudboard', 'manage_options', 'crud', 'crudboard');
   add_options_page(NULL, 'Crudboard', 'manage_options', 'create_crud', 'crudboard');
}

and your anchor tag like

<a class="add_new-h2" href="https://wordpress.stackexchange.com/questions/137953/<?php bloginfo("url');?>/wp-admin/options-general.php?page=create_crud">Add New</a>