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Python 3, 62 bytes

lambda s:['Yes',*s[:-1].split(','),'No'][~(','in s)*('?'in s)]

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The expression ~(','in s)*('?'in s) evaluates to 0 (i.e. 'Yes') if the string does not contain a '?', else -1 (i.e. 'No') if the string does not contain a ',', and otherwise -2 (i.e. the last comma-separated section of the string excluding the last character).

05AB1E, 20 19 bytes

'?åi',¡”€–”0ǝθ¨ë”…Ü

-1 byte thanks to @Grimy.

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Explanation:

'?åi          '# If the (implicit) input contains a "?":
    ',¡       '#  Split the (implicit) input on ","
       ”€–”    #  Push dictionary string "Not"
           0ǝ  #  Insert it at the first position (index 0) in the list
       θ       #  Then get the last item of the list
        ¨      #  And remove the last character
               #  (either the "?" of the original input; or the "t" in "Not")
      ë        # Else:
       ”…Ü     #  Push dictionary string "Yes"
               # (after which the top of the stack is output implicitly as result)

See this 05AB1E tip of mine (section How to use the dictionary?) to understand why ”€–” is "Not" and ”…Ü is "Yes".

JavaScript (ES6),  53  52 bytes

s=>(m=s.match(/(,?)([^,]*)\?/))?m[1]?m[2]:'No':'Yes'

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Commented

s =>                  // s = input string
  ( m = s.match(      // m is the result of matching in s:
  //     +------------>    an optional comma
  //     |     +------>    followed by a string containing no comma
  //     |     |   +-->    followed by a question mark
  //   <--><-----><>     
      /(,?)([^,]*)\?/
  )) ?                // if m is not null:
    m[1] ?            //   if the comma exists:
      m[2]            //     output the string following it
    :                 //   else:
      'No'            //     output 'No'
  :                   // else:
    'Yes'             //   output 'Yes'