Hi,
Death Certificates are usually provided by hospitals/medical center where the person died or by funeral homes/parlors when the person died at home.
Since you are in Abu Dhabi, ask your mother or siblings or relatives in the Philippines to report the death of your father to the local Civil Registry.
Requirements for Registration of Death:
a.Death Certificate that is certified by a licensed medical doctor, or the attending physician, and
b.Signature of embalmer and his/her license number.
Once you have the above, they can go to the local civil registry and ask for assistance to report your father's death and so you can obtain a record of death from them (local civil registry). Since you want to get the death certificate for your marriage abroad, you have to have it authenticated (with ribbon) in the Department of Foreign Affairs (DFA) before your family/representative post it to Abu Dhabi.