Is a father permitted to compel his children to visit him in the home of his second wife, given the children's refusal due to their fear of him and his past treatment of them, as well as his withholding of financial support and his preventing them from receiving government assistance?

Obeying one's parents is obligatory in what is good, and showing kindness to them is a duty. This includes non-Muslim parents, unless they command shirk (polytheism). Obedience to parents is obligatory in matters that benefit them and do not harm the child. If there is a benefit for the father in a matter and no harm results to the child, then obedience is obligatory. If harm is certain to result from visiting the father's house, then this is not required in the future.