The correct answer is: B. She told her friend that she knew where everyone was.
The sentence “She said to her friend, ‘I know where is everyone'” is in the past tense. This means that the speaker is telling someone about something that happened in the past. In this case, the speaker is telling her friend that she knew where everyone was at some point in the past.
The answer A, “She told that she knew where was everyone,” is incorrect because it does not use the past tense. The answer C, “She told her friend that she knew where is everyone,” is also incorrect because it does not use the correct verb tense. The answer D, “She told her friend that she knows where was everyone,” is incorrect because it uses the present tense instead of the past tense.
The correct answer, B, “She told her friend that she knew where everyone was,” uses the correct verb tense and accurately reflects the meaning of the original sentence.