Actually there is no such module as “simpl_cousins”. The module is now in the core code and called “cousins tab”.
Your line numbers are all incorrect for the current version of the cousins tab, so I guess you still have a copy of the old “simpl_cousins” module in use. Disable it in admin, then delete it from your system.
Then check that cousins_tab exists, is enabled in admin, and has the correct access set in Admin > Modules > Tabs.