Answer: A quick shoot-from-the-hip answer: Try a vii dim 7. The inner notes would be D and Ab, and the soprano G (the 6) would be dissonant and resolving down to the F that is part of the vii dim 7. This matches the figured bass and makes a nice movement. The following chord would be a C minor, after the F. The F would do nicely moving down to Eb in the C minor chord.

The G is therefore a "non chordal" tone. The vii dim 7 is the only chord of record until you follow that F with a resolution to C minor.