Are you talking about CogoPoint's label/label style in Civil3D? If so, you might want to post C3D specific question in C3D designated forum here.
Also, do you want to create a label style for point purely in code with C3D .NET API (because this forum is for Acad .NET API programming)?
IMO, it would be much better to create a desired point label style manually and include it in drawing template, than having to create label style in code. Regardless, if it has to be created programmatically, I'd still do it manually so that the LabelStyleTextComponent for the point elevation can be set up to show show elevation in foot, even the elevation value is in meter. I would: create a Expression, something like "{Point Elevation}*3.28" and then set it as the content of LabelStyleTextComponent (for Point elevation). Once I satisfied with the manually created LabelStyle, I could then go ahead to use C3D .NET API to create new LabelStyle (or maybe, modify existing one?), and the code would set the coorsponding TextComponent to use the Expression as its content. In fact, I could also use code to make sure/create the Expression that convert meter into foot.
Not sure if this answer helps or not.