What are the realistic challenges for Life Insurance Payout for someone if the deceased appears to be the Victim of a Supernatural Attack?

Insurance companies tend to be very bureaucratic and would probably just go with whatever the police determined happened here. Many life insurance policies won't pay out on a suicide but would if it's determined to be a homicide. Both killers and suicidal people have been known to try to contrive strange, occult scenarios. But 'death by vampire' isn't what the medical examiner would put on the death certificate.

They would receive full benefits because the insurance company is not likely to attempt to prove, in court, a fatality was caused by a supernatural attack.