How can someone deal with a situation when a Nadhr has not been fulfilled and they have forgotten the conditions they had made? Would they only pay Kaffarah?
If you are sure that you made a Nadhr, then you must fulfill it in every possible way. If you are not sure that you made a Nadhr, then nothing is obligatory on you.
If you did a Nadhr and you deliberately did not fulfill it, there is a Kaffara on you which is: feeding ten poor believers or clothing them. If you are unable to afford that then fasting three days.
Wassalam.