Which sentence is correct?

a) she is certainly a loving person, who talks to everyone friendly. however, she has made a cost mistake, so unfortunately we have to fire her.
b) she is certainly a lovely person, who is very friendly to everyone. however, she has made a costly mistake, so unfortunately we have to fire her.
c) she is certainly a friend person, who treats everyone lovely. however, she has made a costly mistake, so unfortunately we have to fire her.
d) she is certainly a love person, who treats everyone lovely and friendly. however, she has a made a cost mistake, so it is unfortunately that we have to fire her.