How did Nigeria gain independence?
As a British colony, the country became a Federation in 1954 and increasing degreesof internal self government were introduced by the British until the country became fully independent in 1960. There were two military coups in 1966. then in 1967 the Eastern Region seceded setting up the Igbo state of Biafra and civil war broke out in which 1 Million died. the war lasted until 1970 when Biafra surrendered and returned to Nigeria which has remained independent since but with several military coups and continuing ethnic and regional tensions.
Britain colonised Nigeria towards the end of the nineteenth century, after a forty-year war. Coastal areas were colonised first, then Britain began making inroads into the interior. A protectorate was established over northern Nigeria in 1900. Nigeria did not gain its independence until 1 October 1960.
No British monarch visited Nigeria in 1960. Queen Elizabeth II was the monarch then, but she did not go to Nigeria. 1960 was the year Nigeria gained independence. Princess Alexandra, the cousin of Queen Elizabeth II, represented Queen Elizabeth II at the independence ceremonies in Nigeria, so that may be the answer you are looking for.