Is it better to perform the Ishā prayer in the mosque or at home, given the presence of a young daughter who might not be well-behaved during the prayer and could cause disturbance?

The demand to pray in the mosque is fundamental, but if bringing the child causes disturbance to the worshippers, then do not bring her. If it is possible to leave her safely at home and pray in the mosque, then do so. However, if you fear harm to her by leaving her alone, then there is no blame upon you for staying behind and praying at home; for fear for one's family and child is an excuse for not attending congregational prayer.