looking to pull out out last names only

[mcgonma]

I'm looking to pull into Column B the last name only from the "full name" column (column C).
Right now, in Column B I have the formula =UPPER(MID(C3,FIND(" ",C3)+1,50)) to pull in the last name from the full name that is in column C.
The problem is that when column C has a middle initial or a nickname, column B ends up having the middle initial and the last name.
For example, if Column C has John "Buster" Jones, I get "Buster" Jones in column B but I only want Jones; or if Column C has Mary T. Smith, I get T. Smith in Column B but I only want SMITH
Is there a better approach so I only get the last name?

[NBVC]

This gets the last "word" in a string and upper cases it.

=UPPER(TRIM(RIGHT(SUBSTITUTE(C3," ",REPT(" ",100)),100)))