The scene with Claire's mom has not been implemented yet, despite having the images on the game files. The only "bad end" on Rivermont is when you take more than 3 days to arrive at the castle, and the Pigboss is having its way with Marie (who btw is the girlfriend of that guy who drowns on the other prologue). When the Rivermont Bad End is implemented, it will be achieved if you also take more than 4 days to get to the castle, at which point the horde will take over the city.
The best way to get these scenes is to go to the destroyed city with the boat and then immediately return, which will make the day pass, and only get (or not) to the castle after the period above. As for getting to the castle, the two ways are: talking to the Chef Pigman (don't know what to call it) and get the cooking ingredients (spread throughout the occupied city), and it requires (if I remember correctly) 4 seduction and 4 defiance and 4 depravity? These can be gotten in the city and via praying in the altar. The second way is through the sewer, and requires some itens on the occupied city (rope, bandage and shovel), energy (just have some food on you), and 3 intrigue (can be gotten via talking that girl out of suicide using science and facts, and via praying). When getting stats on the city, being deprave enough gets extra stats from the old man and the scene with that redhead girl.
