Can someone just explain!!!

Before my mother passed away she was receiving an amount monthly from my father's pension( He passed away before her) I am the only heir on her will and fail to understand the policy that states that those funds are the GEPF's to keep even though I am my parent's surviving heir. If I understand correctly, whatever remains of my dad's pension is not claimable. He worked hard just so that one day his funds could end up at the GEPF leaving his offspring with not even a monthly grant. Can I just get someone to explain how this process works.