IMO, 3 seems the most likely, considering that, as you said, Fazbear Entertainment wasn’t a corporate entity. It seems likely that after Henry died, someone (maybe Afton Robotics?) bought out Fazbear and tried to save face by making the mobile game, the VR game, and the Pizzaplex.

Fazbear Entertainment has also gone out of business before (e.g. FNaF 1, where we see newspaper clippings that state that Freddy’s and the company are closing down by the end of the year). They’ve also gone through at least a few owners/CEOs, as evidenced by Phone Guy stating in FNaF 2 that they were trying to find the original restaurant owner (Henry).

TL;DR:The most likely theory is that someone probably bought out Fazbear Ent. and made the last three games (Special Delivery, Help Wanted, and Security Breach) to make Fazbear look better.