For Windows 95, you have the following options:
IE 5.5 SP2 (5.50.4807.2300). If you go this route, the last hotfix is "KB867801: Cumulative Security Update for Internet Explorer" which covers security updates through bulletin MS04-025. IE5.x (and even 6) run rather spritely on old hardware, but I have no idea how well it parses pages these days as I haven't used it in years. I believe 5.5 is closer to the 6.0 rendering engine than 5.0x, for what that's worth. Older version of Maxthon classic will give you tabs and a pop-up blocker.
Gecko: Go with ToastyTech's fix mentioned above - these are more modern than Firefox 2.0 or SeaMonkey 1.1.19 as he compiled it against SeaMonkey 1.9.20pre and Firefox 2.0.22pre. Firefox continued to see nightlies for six months after the release of 2.0 (the last was 2.0.0.22pre-20090415). Of course I'm not sure what you gain from that - but might as well go with it.
I was actually surprised to learn that opera petered out at 10.10 - since 10.63 runs fine on NT4. I'm now curious as to what the missing dependencies are...
RE: OffByOne - when I found that years back I thought "oh hai! a modern, tiny browser for old systems". I think I found it about the time it was seemingly abandoned. The modern soon disappeared.
Of course, with 95C - are you using the webby shell? If so, and it's running acceptably, I doubt you'd see much performance degradation from moving to 98 and you'd get expanded compatibility. (You could still go 98 with 98Lite).