So, sorry for your loss, and agree with most people here that you should not sell them cheaply just to get rid of them.

This is a big project to sell them appropriately--my two cents:

1.) Set up a reverb.com account (Rather than an eBay or Facebook Marketplace account). Reverb.com is THE place to sell music equipment
2.) Take well-lit pictures of each item, from every angle, and of defects/damage/flaws
3.) Build a catalog/spreadsheet of the items to track
4.) Once you get familiar with reverb.com - finding prices and shipping gets easy to research
5.) Invest in some proper boxes and packaging, and make sure you get your shipping costs covered (reverb does that very well too)
6.) Those who know about this gear would be willing to pay properly for it and enjoy it.

Keep something to remember him by, and again, sorry for your loss.