Given your now complete information and presuming that you are on a discounted fare which is non-refundable / changeable:

1. Your wife will receive a credit which she can use within one year. At the time she uses the credit, she will pay an additional $150 penalty. So, if it's a $500 ticket, she will have a $500 credit and when she uses the credit, she will pay $150 above that.

2. If you change your return now, you will pay $150 + fare difference, if any. If you way to same day, you will pay less, but there may be no availability.