I highly recommend using Homebrew and pyenv and following this article for setting up your local environment:
https://jacobian.org/2019/nov/11/python-environment-2020/
Here are the steps for installing cyvcf2:
$ python --version
Python 3.7.5
$ python -m venv .venv
$ source .venv/bin/activate
$ export LDFLAGS="-L/usr/local/opt/openssl/lib"
$ export CPPFLAGS="-I/usr/local/opt/openssl/include"
$ pip install cyvcf2
$ pip freeze
click==7.1.2
coloredlogs==14.0
cyvcf2==0.20.0
humanfriendly==8.2
numpy==1.18.4
Here are the steps for installing tabulate:
$ pip install tabulate
Now you can run the code:
$ python run_me.py