How do I claim for dependent care credit (child) when my spouse doesn’t have an earned income in the year but is looking for a job ?

You can't.  For the dependent care credit, you can count care provided so you can look for a job as qualified care, but the dollar amount of the credit is limited by you or your spouse's earned income.  In other words, if you look for a job but never get one, you can't use the credit.