You're absolutely right in bringing up this comment that in reality it would make more sense to bring a female employee to tag along with gin. However, he is also aware of how the other employees are. In the past, they made fun of Vidhi (put glue on her chair, made her believe Dev was married to someone else and etc)..so it wasn't natural for him to take someone with him that puts him in a stronger position. Furthermore, others were equally drunk. So perhaps he didn't think it'd be a good idea as it'd make things worse in front of HP. At least, Dev knows how the father is and how to handle him in a mature manner.
In Dev's defense, they did portray HP trusts Dev. HP even wrote a letter to get Dev's opinion about Vidhi's marriage and that alone says a lot about the respect HP gives to Dev. So I think Dev knew that HP wouldn't get mad if he brings Vidhi himself (and not bring a female friend along).
That's my thoughts of course. And the way HP reacted today is 100% justified. Seeing your daughter in someone's arm in the middle of the night while she is drunk is not any father's dreams..so I'm with him on this one.