What should I do with the necklace my mother interacted with, and how can I make my mother vomit the sorcery in her stomach and get rid of what is in her left leg?

The necklace belongs to your mother; she can dispose of it as she wishes. Your mother should perform ruqyah (definition) on herself, and you should also perform ruqyah on her with Al-Fatihah, Al-Mu'awwidhat (Surahs Al-Falaq and An-Nas), and Ayat Al-Kursi, for ruqyah is beneficial for all illnesses, by Allah's will. Your mother should continue to consult doctors, in compliance with the Prophet's (peace be upon him) recommendation to seek medical treatment. If she frequently performs ruqyah on herself with Al-Fatihah and Ayat Al-Kursi over water and drinks it, or if someone else gives it to her to drink, it is hoped that this will free her from any magic in her stomach or body. There are two ways for your mother to be freed from what she is suffering: consulting doctors and using beneficial ruqyah. Let her be patient with what has afflicted her.