Depending on the time period, anyone between the Egyptians, Hyksos, Nubians, Libyans, Persians, Assyrians and the Romans, and indeed the British, since they all at one point were the official rulers of Egypt.
I have no idea why citizens of modern Egypt, which didn’t get formed until 1953, would be more entitled to up to 3500 year old artifacts more than the then actual owners (agree with the means or not)
Mummies are maybe a bad example, as one could argue, that bodies should be by their grave.
And in fact modern Egyptians are more Arabs — the Copts are closer to, but still very far from, the ancient Egyptians.