Was Nyasaland and Rhodesia renamed?

Yes, the region of Nyasaland was renamed Malawi when it gained independence from British colonial rule in 1964. Rhodesia, a region that was under British colonial administration, was renamed Zimbabwe when it gained independence in 1980.

Who was the Nationalist leader(s) of Nysasaland and Rhodesia, and what was the political party(ies) called?

In Nyasaland (now Malawi), the nationalist leader was Hastings Banda, who founded the Malawi Congress Party (MCP) in 1959. Banda played a key role in the country's struggle for independence from British colonial rule and served as the first President of Malawi from 1966 to 1994.

In Rhodesia (now Zimbabwe), the nationalist leader was Robert Mugabe, who was a founding member of the Zimbabwe African National Union (ZANU). Mugabe became a prominent figure in the fight against white minority rule in Rhodesia and later served as the first Prime Minister of Zimbabwe from 1980 to 1987 and then as President from 1987 until he was ousted in a coup in 2017.

Which colonizer gave Nyasaland and Rhodesia independence and who was the prime Minister of the colonizer at that time?

Nyasaland (Malawi) and Rhodesia (Zimbabwe) both gained independence from the United Kingdom.

Nyasaland gained independence on July 6, 1964, under the leadership of Prime Minister Harold Wilson of the UK.

Rhodesia gained independence on April 18, 1980, under the leadership of Prime Minister Margaret Thatcher of the UK.