her. Ginsburg thinks it should be "His".
mourning and lamentation. Note the Figure of speech Paronomasia (App-6). Hebrew. taaniyyah vaaniyyah.
Related Commentaries of Lamentations 2:5
Lamentations 2:5
5 The Lord was as an enemy: he hath swallowed up Israel, he hath swallowed up all her palaces: he hath destroyed his strong holds, and hath increased in the daughter of Judah mourning and lamentation.