I have a chapter from a teenagers point of view which is written in 3rd person. The male teenager is talking to his mom. Do I call her mom or her name? I already have a different character who has her own 1st person chapters which is why I've not gone down the 1st person route. Most of the story is 3rd pov.
Even in 3rd the narration should reflect the POV of the focal character. That is, as long as we're talking limited 3rd and not omniscient, which I'm assuming is the case since you mention that the chapter is from a character's POV.
When I was a teen, I knew that if I ever dare to call her by her name, instead of mom, I would have faced consequences. I think it's something really cultural how to address someone's parents, but at least in my country is kinda disrespectful, and people looks badly when a son or daughter does that - of course there are more "relaxed" families than others. I would go for a nickname or just mom, but can also be used to depict some degree of tension in the family of your story to be called by name.
In Sweden the norm is to call your parents "mom" and "dad". However, my brother and I have always called them by their firsts names (for no real reason, it just happened somehow). So I would say that things work differently in different families (and different cultures).
It depends who your following at the moment. Maybe the first time the reader meets her say "his mom, (name)" then say "Mom" if it's following the teen, and her name if it's following another adult.
If she's going to be an important character, you could always have the MC asking for her at her workplace. Maybe the MC is sick at school and over hears the nurse calling for a, "Jane Doe".
It depends on what role they play in the story. In my current WIP, the MC's parents are "mom and dad" because it's all told from his perspective, neither character has a major role in the story and it makes no sense to call them anything else. When you have a lot of moving perspectives, it makes a little more sense to have some people call them other things depending on their relationship.