Is it permissible to demand the price of gold at the market rate at the time of filing the lawsuit, or is that considered usury?

Disputed matters are to be referred to the Sharia court, not to a fatwa. If the gold mentioned in the list is in the wife's possession, she has no right to claim its value. If it is proven that it is a debt owed by the husband and the gold was uncrafted, then he must return its equivalent. However, if it was crafted and its guarantee is proven, then he owes its value at the time of payment.