file_get_contents | escaping doesnt show the page

Well, esc_html() doesn’t echo/display the return value (escaped string), so you need to call echo manually:

echo esc_html( $FileContents );

Update

If you actually want to filter the list of allowed HTML tags in the variable’s value, then you can use the WordPress’ KSES functions like wp_kses_post() and wp_kses_data():

echo wp_kses_post( $FileContents );
echo wp_kses_data( $FileContents ); // allows basic HTML by default