Is money taken from a charitable committee forbidden (haram) or permissible (ja'iz) with sin, after lying in some details of the assistance request, even though I am one of those eligible for Zakat?

Lying is forbidden, and it is a path to Hellfire. If the money taken was Zakat money and you were among its rightful recipients, then it is permissible for you to take it, while incurring the sin of lying. However, if it was other conditional money and you did not meet its conditions and lied about them, then it is not permissible for you, and you must repent, return it, and seek forgiveness.