In addition to the audio driver, here is the information about modem and wireless drivers for C500 series.
Install the Microsoft UAA driver (SP32646)
Download and install Conexant modem driver (sp33442). This will give error message and also will create a folder C:\swsetup\sp33442 which contains extracted driver files.
Use the same method which you followed for installing the audio driver through Device Manager.
You can refer the session: 10011011170394557529 for additional information.