Valmiki Ramayana Ayodhya Kanda Sarga 10 Shloka 4

सुहृच्च also a friend, अर्थकामा च desiring to fulfil the resolve, सा मन्थरा that Manthara, तम् that, सुनिश्चयम् firm determination, निशम्य having heard, सिद्धिम् acomplishment of the objective, प्राप्येव as if, परमप्रीता highly pleased, बभूव became.

Manthara, Kaikeyi's friend, too, driven by a strong desire to fulfil her resolve was highly pleased and on hearing the firm determination of Kaikeyi, felt as if the accomplishment of the objective was at hand.