Is a mother sinning by owning a satellite dish that her daughter's husband uses to watch forbidden channels, knowing this, if concealing the remote control would cause family problems?

Your mother must prevent your husband from using the topless shower to watch forbidden things, by hiding the remote or by other means, otherwise, she would be sharing in his sin, because Allah Almighty says: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." The best course of action is to get rid of the device permanently by breaking it.