#1 is Margaret Kathleen Ann Johnson (b. 1959) is the author of All I want and Next door to love.
#2 Margaret M. Johnson (b. 1944) is the Irish-American author of cookery books.
#3 Margaret Johnson (b. 1926) is the author of 18, no time to waste.
#4 Margaret K. Johnson is the author of Japanese Prints Today: Tradition with Innovation.
#5 Margaret Johnson Speed 1802-1868 was the author of Alice's alphabet.
(WorldCat attributes a miscellaneous collection of works to Margaret M. Johnson 1944-, but from her own website she seems to write only cookery books, so the others have been left unassigned.)