You can customize the password reset notification email (sent by this plugin) from the following admin interface:
Simple Membership -> Settings -> Email Settings -> Password Reset
You can use most of the standard email merge tags to put dynamic info in that email.
The WordPress’s Password Change Email
WordPress may send an auto-generated password changed email since the WP user’s password is updated.
You can disable/customize that WordPress’s auto-generated email using a plugin like the following: