You mentioned Medicare, let Medicare handle the bills first before you take on the payments on the remaining amount. It should show "Billed to Medicare" or pending information from Medicare. That would be covered under the Part A, for the emergency ER care.
I agree with one said above, put them all in an envelope and let the family friend or financial advisor look over it and they can tell you what you need to do. Is your mother letting you take care of the family finances? If so, that is a lot to put on a young girl like you to manage family finances in order upon one's death. Be sure to have someone who experience this "mess" give you a guide in what to do and so forth.
Funeral expenses are not cheap. Hope your father has prepaid his funeral expenses or life insurance policy or savings saved up for that purpose. I think SS will only pay 100 dollars toward the funeral expenses. And the living will......I can not say this enough about this, it would make a heck of a difference.
I've been hearing cremation is the cheaper route to go rather than body viewing, casket, funeral and burial services, etc.