Lowest DH on fail-op NG?

Folks, Recently I talked to a retired A320 instructor and examiner, and he let me know their DH for CAT IIIB approaches were fixed to 17' RA at his particular airline, because he said "it's the lowest altitude from where it could be shown the aircraft would go around without touching the ground". I wonder if there are similar examples of such values for the NG, and what they would be. Related question, how would a procedure look like that involves both AH and DH? I understand IIIB doesn't need DH (does that imply I use AH? Or is IIIB always linked to AH, regardless of DH usage?), so what are the actual options for IIIB -- DH, no AH- DH and AH- AH only- combination of any above? Insight appreciated.