My ex mother in law died 2008. She had life insurance and I want to know if her two grand kids where on the policy?

You need to speak with the estate's executor.

If the kids' whereabouts were known, they would have been contacted by the insurance co. Minor children are rarely added to a life insurance policy.

It would be up to the carrier to attempt to find the beneficiaries.

The insurance companies, will write the check listed to the named beneficiaries,

The insurance companeis attempt to contract them.

The grandkids, or their guardian (or parents) can contact the insurance company and verify.