How to fix ‘Call to undefined function do_settings()’ error?

Q1: [H]ow to fix the error?

Stop calling the do_settings() function in this line. It is not a WordPress function and it is apparently not a function that you have defined. Perhaps you meant to use one of these functions.

<?php do_settings( 'mhomepage_option_group' ); ?>

Q2: [W]hat is the correct file name in <form method="post" action="options.php">?