These are quotes from some different sources.
"In Greek mythology Memphis was the wife of Epaphus, mother of Libya, and sometimes the daughter of Nilus. She and her husband were the legendary founders of Memphis, which bears her name."
"MEMPHIS was the Naiad Nymph of the well or fountain of the Egyptian city of Memphis. She was a daughter of the
River Nile, who married Epaphos the founder king of her name-sake city."
MEMPHIS (Memphis). A daughter of Neilus and wife of Epaphus, by whom she became the mother of Libya. The town of Memphis in Egypt was said to have derived its name from her. (Apollod. ii. 1. § 4.) Others call her a daughter of the river-god Uchoreus, and add that by Neilus she became the mother of Aegyptus. (Diod. i. 51.)
Source: Dictionary of Greek and
Roman Biography and Mythology.
"When Epaphos was ruler of the Aigyptians (Egyptians), he married Neilos' daughter Memphis, and in her honour founded the polis of Memphis, and fathered a daughter Libya." - Apollodorus, The Library 2.10