i THINK MIXTURE OF ALL THE 3 OPTION WILL HAPPEN.
option 1 he thinks piya married ruled out as he knows now that piya is puja and puja is not married to rajat as he himself persuade rajat to propose puja,and about daughter she already said by body act she is his daughter now he belives her or not it is secondary question.
option 2-he is not sure she also loves rajat or not but he knows rajat side story so he may be in double mind but i doubt he will doubt her for affair with rajat.
option-3 they unite and happy fore ever cant happen so early as it is ekta's serial if they unite now what story they will say further to glue the viewer to the screen?
so my prediction is he will become first very happy by seeing her alive and will be very angry for hiding herself for all 6 years and keeping him away from his daughter for so long,he had equal right to know about his daughter and will have hot conversation with Priya and will ask her to explain why she kept herself and her daughter away from him?
Priya will explain everything, after hearing her side of story he wants priya to come back to his life but priya will refuse and will say now as such he has moved on with his life, she cant destroy her sister's life so it is better they stay separate and she is happy with her life,and now she is happy that he knows he is pihu's father so she is out of guilt that she didn't give her daughter her rights to know her father.
She may request him not to say all truth to rajat and his family as she dont want any special treatment from any one.here Rajat will try to call Ram and priya both for delaying in party,but Ram will get attack by assuming she might be in love with rajat or she will say to him he has moved on she also wants to move on and will ask ram not to revel truth to the people as it will destroy life of Ayesha so it is now better he forget her .Ram will clarified to her that she got marry to Ayesha just to save her dignity in socirty as she is pregnant with sid's child and he took this step only to please priya's soul so that she can be happy somewhere sitting in haven if he knew she is alive he could have never took this step and by law she is still his wife so marriage with Ayesha becomes automatically illigmate and he don't have any physical relation with Ayesha and he don't love her.they will come home and Ayesha will taunt her that she came to ruin her life so our mahanta devi will try to sacrifice her marriage and will lie to Ram that she loves rajat she moved on with life and he should also moved on with Auyesha than will come twist and turns and story will go on ekta style the will meet,they will seperate,there will be MU there will be drama but there will be no end to this story by taking drastic twist and turn the story will loose its orginal charm and than come leap again and sisila will go on...