My Grandmother forgot her Icloud and Apple ID

Dears,

Kindly I need help! My Grandmother has an I phone 5 and she even doesn't know her Apple ID and her Icloud ID.

She has her find my I phone turned on. She cannot turn on her I phone. They are asking her about I cloud ID.

What can I do? This is so complicated.

I would appreciate a fast reply.

Thank you in advance.

Regards,

Layal