BuddyPress.org

Editing core files is never the best way to go of course; you’ll lose your customizations once you upgrade BP.
Better is it to redefine the function that is called. You would find the place where bp_get_options_nav() is defined, copy the function and place it in your bp-custom.php, rename it to something like my_bp_get_options_nav() and then make necessary customizations.

bp_get_options_nav() is defined here, BTW (starting from line 91).