Makes sense that life insurance firm is certain the named party is dead before they pay out to the named benificaires --what seems to be your hang up is sorting out what the insurance firm needs to move the ball forward.
Odds are they may want an "offical" death certificate--with a raised seal or whatever affirmation is locally provided, not just a nice copy --thier own forms probably notarized and some way to link the names the person used? --- Upon the insured's death, the insurer requires acceptable proof of death
before it pays the claim. The normal minimum proof required is a death certificate, and the insurer's claim form completed, signed (and typically notarized)