Selfhosted

Build her a server, install it at her house, set up some sort of automated DVD ripping mechanism so that she can digitize her own collection, wait for the inevitable tech support call, then go spend a Sunday afternoon fixing her server and digitizing her collection for her while she makes you dinner. You get to call it "quality time", and you get fed while keeping her happy and her collection as far away from yours as possible. Win/win, everyone is happy.

Well, just don't host them, what she gonna do? Tell the police ?

It's my library. I only approve shit that I want to be on there.

My users know this (including family). If they want to be picky they can run their own shit. I've denied plenty before.

An alternative answer is to "approve" it in overseerr, but remove the request in radarr. Or setup a blacklist for the name. Then just say that the tools can't find the movie, nothing you can do about it.

If you agreed to host her collection carte blanche, that's your failure to manage expectations.

The better approach would have been to make an X GB partition (whatever you're comfortable allocating) say there's a specific amount of space available for family use. When it fills up it fills up.

I would be sincere:

Movies take too many space in SSD and too many resources to host, therefore I'm not going to host movies I disagree with. And if she really want this movies to be digitalized, I would give her a choice to buy new hardware (probably SSD) to be dedicated to her.

You rip them and provide them to a community that will then re-dub them into something fun. Hilarity ensues.

Just explain your reason why you don't allowed it or give her your recommendation movie that similary with her movies

You can use this as an opportunity to have a conversation about what it is about those movies that she likes. This could open up to a larger conversation where you can connect and grow your relationship as mother and child. Or she might just say something vague and simple and you can ignore the movies while they sit in a separate library.

"Sorry, disc must be scratched"

Christian propaganda? Destroy it and hide the evidence.

The less of that evil in the world, the better.

I usually just say " odd, i cant seem to find that one"

Well, my mother has asked me to digitize her collection too and have me host it. Originally, fine, you give your movies to me, I host them, same thing.

Did your mom buy your computer and hard drives? I doubt it. You spent your own money, right? So she's giving you a whole bunch of stuff which is consuming your space. Quote out the cost of buying components for a separate server for her with her own drives. When she buys the parts, build her her own server and put her stuff on it.