the spelling
No, the spelling of "dilemna" has not been changed to "dilemma." "Dilemma" has always been the accepted spelling, whereas "dilemna" is an incorrect variation that some people mistakenly use.
The spelling was changed around about 1952 or 1953
The correct spelling is "Vietnam." While "Viet Nam" is often used in official contexts, particularly in Vietnamese, "Vietnam" is the more common and widely accepted spelling in English and international usage. The single-word form has become standardized in most references and publications.
Media coverage of wars changed from Vietnam for better.
The correct spelling of Vietnam is V-I-E-T-N-A-M.
It became a communist but united country,
Two things that have changed since the Vietnam era are communications and the cost of living.
The word "business" has not undergone a change in spelling. It has been consistently spelled as "business" throughout its usage, originating from the Old English word "bisignes" meaning "anxiety" or "care."
Because it changed what had been a simple guerrilla war in South Vietnam into an open conventional war in both South VN and North Vietnam. There was no open direct hostilities against NORTH Vietnam prior to the Tonkin Gulf.
The Vietnam war
In addition to the spelling error, this question is illogical.