Hello Arun,

See if there is the column for Father's name in the OMR sheet of AIBE XV or it is required to fill the Father's name and you have not filled it out then this might be the reason for disqualification, because generally the candidate is supposed to fill out all the details required in the OMR sheet and there is  a software through which the OMR sheets are scanned for making result so if it found any incomplete OMR sheet then it will throw an error and might disqualify the candidate for incomplete details. But if there is no any requirement for Father's name then you don't have to worry because the main thing is the OMR sheet should be completely filled with correct details.

For more details about AIBE XV kindly check out the link given below :-

AIBE 2020: XV (15) Dates (Out), Application Form, Eligibility, Syllabus (careers360.com)

I hope this information helps you.

Good Luck!!