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.