As salaamu alaikum. Which name would be gender correct for a non married Muslim woman? Jennah Sameeha Rahman or Jennah Sameeha Rahmah

Alaikumassalam wa rahmatullah,

Rahmah (also written Rahma) is the correct one. You cannot use Rahman as a name unless it is preceded by Abdul (for a male) or Amatul for a female, which mean "servant", "slave", since Rahman is considered a synonym of Allah. Thus you could also use Jennah Sameeha Amatulrahman. Amatulrahman can be spelled as Amat al-Rahman, Amat ar-Rahman, Amaturrahman and others.