2.8 ~ 3Yrs is too long a time for all these. Either previous company was naive or this company is.
Just tell your friend to relax, tell her that UAN/PF/EPF process were not moving ahead. Relieving letter need to check in mail box, if available will share.
Basically they may ask this to check if they are not involved in dual employment. Easily she can get out by showing inward transactions happening in her bank account.
No need to worry about this. At times company culture triggers us to abscond.
I have seen abscondings very very closely in global conglomerates. No one is bothered about it until you have some trade secrets. Relax!