Policy payout

My grandmother passed away and had a policy with freedom life,she made my mom her beneficiary (Daughter in law)Now they rejected the claim.My grandma could hardy read nor write and at some point ddnt have a phone..She needed to add some people on her cover and my mother helped her, ow they saying there is a possibility that my mother is the one who open the policy and been paying .How though when recently they called my granny and she confirmed itsbher policy and she pays with her grant money,we even have that on record on her phone ..