All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If you see your mother watching on television programs containing forbidden matters, then you have to advise her gently and leniently. If she takes heed, then praise be to Allah; otherwise, just leave her.
Ibn Moflih said:
“Ahmad said in the narration by Yoosuf ibn Moosa: One should order his parents to enjoin good and forbid evil, and he said in the narration of Hanbal: if he sees his father doing something that he dislikes, he teaches him without violence or abuse, and he should not speak to him in a harsh way, otherwise he should leave him because a father is not like a stranger [a person who is not a relative].” [End of quote]
Merely giving her some food or drink or anything permissible is not considered as helping her in sin. If she asks you for anything of this, then you are obliged to obey her in doing so because it is obedience in what is permissible.
For more benefit on correct approach to give advice to parents or elderly people, please refer to Fatawa 297928, 343564, 351385 and 13288.
Allah knows best.