What is the ruling of Islamic law regarding a wife who demands her husband return the salary she spent on the household for two years, claiming she paid it out of shyness, not willingly, after she used to taunt him about his failure to find work?

If a wife spends on her husband voluntarily, she has no right to demand it back. However, if she spends with the intention of being reimbursed, she has the right to demand it. If she claims this, she takes an oath and is entitled to reimbursement for what she spent. Her right is established even if the husband was in financial difficulty at the time of the expenditure.