They are two words conjoined to be one.
in-house - two words, hyphenated.
"Handmade" is one "compound word", sometimes hyphenated as "hand-made"; not to be confused with handmaid, which is NOT hyphenated.
Underdeveloped should be written as one word, not two words or hyphenated. I hope this answered your question. :)
Businessmen is often written as one word. It can be two words or even hyphenated
it is two words but if hyphenated they become one word
One word is fine.
Race day is two words.
It is not one nor two words. It is hyphenated, just as it is written in the question.
A house after set up
The word well-being is 2 words, usually hyphenated.
It can be written as one word or two or as a hyphenated word, all are correct.
Compound words whose elements have not been combined, like toothbrush, into one word are generally hyphenated.