Question: Who is the paternal grandfather of Louis D'Albret?
Answer: Charles I of Albret

Charles II d'Albret (1407–1471) was a French magnate, administrator, and soldier. He was the son of Charles I of Albret and Marie de Sully. His father died in 1415 at the Battle of Agincourt, leaving the younger Charles as lord of Albret and titular Count of Dreux, titular count since after Agincourt the lands of the county of Dreux were in English hands