estranged sisters that were poa's,tell me insurance policy no good,mother already buried

i have 2 sisters that have not communicated with me from 1997,and my mother b4 she went in nursing home had indicated she had gone to local funeral home and signed a policy over for prepayment of her funeral…my sisters have been her power of attorney since 2000,and are now telling me even though my mother is already buried that the policy is no good..they want my brother and i to fork up money….but we have no proof as to any of this…and i reluctant to trust either of them…