Dear loving granddaughter,
It is lucky your grandma has a caring person like you. Thankyou for the wonderful description. Prima-facie, it appears that she is suffering from late paraphrenia, It is a psychosis of the old age and needs to be treated with antipsychotic drugs, but in a lower dose than usual adult doses. The GOOD NEWS IS that it has a good prognosis and these symptoms of your grandma will recover soon.
Next Steps
Please get her treatment started at the earliest by a psychiatrist.