What is the ruling on the ill suspicions and negative assumptions originating from the grandmother, her surveillance of her granddaughter's actions, her instructing children to take others' possessions, and her assisting her husband who curses the Divine Being and has divorced her repeatedly?

Your grandmother and her husband are in grave danger. The husband's cursing of Allah Almighty expels him from the fold of Islam, and it is impermissible for your grandmother to remain with him. Furthermore, his divorcing her three times necessitates their separation. Therefore, their case must be brought before the Sharia court for separation. As for your grandmother's behavior of having ill suspicions, watching TV series and listening to songs, and commanding the children to transgress, this is a reprehensible act from which she must be advised gently and respectfully, while still maintaining good companionship with her due to her right to filial piety.