The typical scenario is that passengers can just take another train. Depending on the ticket, the railway is responsible for refunding cost for alternative transportation (EU law), but there can be frustrating edge cases where people are left stranded, because there is no alternative, but a lot of bureaucracy. The railway may be responsible for refunding accommodation then, but I think this would not necessarily be the case for monthly tickets, student tickets and so on, when there is no explicit booking for a canceled train like with a regular ticket.
My most memorable train experience in Germany was when Deutsche Bahn left me in Munich in the middle of the night. I had a connection there but my first train was ~10 minutes late, and my second train had already left. So I spent the whole night at the train station until ~5am when I could catch another train in the direction I needed. I've taken many train trips in the Czech Republic, and that has never happened.
I never take the last possible connection of a day, because of this risk.
DB will pay a Taxi or Hotel in such cases. Just had them pay my Taxi home last week.
What I meant was that the buses are provided if there's no other option, like another train.
In some cases, but not always. Probably depends on multiple factors.
The ticket you bought has a ToS attached to it, but basically it boils down to that DB is only required to get you from A to B, but you're not entitled to any specific mode of transportation other than "preferably by rail". While the train may have ended surprisingly, since other trains are still running, DB's opinion is that you can figure out the rest.
In the Czech Republic, what would happen in that case would be that the railway company would shuttle the passengers to their destination using buses. This doesn't happen in Germany?