First of all, I'm sorry for your loss. It was my mother's 90th birthday on Sunday, and the absence of my farther (who died nearly seven years ago now) was still keenly felt.
As to the photographic gear, I'm sure there will be a market for it if you have no use for it. Especially if it is well looked-after; with such a vast collection I suspect many items were probably only lightly used.
Depending on how much you know about Pentax, separating the lenses into their respective series (the several Takumar variants, SMC Pentax, Pentax-M, Pentax-A, Pentax-F, Pentax -FA, Pentax-DA and Pentax-DFA) and listing them by focal length and aperture would be a great start. All that information is written on the lens.
With the 35mm SLR cameras, broadly speaking there are three basic categories: M42 screw mount, K-mount film, and K-mount digital. I would start there.
Then of course, it's also possible there is some medium format stuff in the collection: 645 and 67/6x7.
If this is too much information, don't worry! There is plenty of help here if you're willing to ask