Okay, there are a few things I would try. First, try installing the newest version of MPC-HC, which should come with its own internal LAV filters.
https://mpc-hc.org/downloads/

If that doesn’t work, then you can manually install LAV Filters and add them as external filters in MPC-HC. You can download them from http://www.videohelp.com/software/LAV-Filters. The installation may also prompt you to install LAV Splitter and LAV Audio, leave them checked. In fact, you can go ahead and leave all the components checked, it should be fine. Then, in MPC-HC, go to Options -> External Filters, select Add Filter, and add “LAV Splitter”, “LAV Splitter Source”, and “LAV Audio Decoder”. Double clicking on any of these after you’ve added them should bring up their options, so double click on “LAV Audio Decoder” which should bring up your bitstreaming options.