Typically in modern literature it's spelling is
holmes
In the McGraw-Hill Slang Dictionary it states:
Holmes:
n. one's pal or friend. (A variant of homes. Usually a term of address.)
What do you think about that, holmes?
Additionally according to RONSROOM1 from bdwf.net:
When I was working Latin Kings area of Chicago in the 70's...........
Homes was plural
Holmes was singular
Urban Dictionaries take on it is:
Holmes
Gangster slang. What you would call a good friend, a stranger, or even mockery against an adversary.
Wassup, holmes.
You got a problem with it, holmes?
Homes
a term used to describe a friend or person you know.
What up homes? Que pase homes?
The debate continues...