if close of escrow is past and nothing happens contract is ended. What happens to earnest money?
Can seller keep it due to buyers not performing since close of escrow is past.

Depends on your contract wording and your individual state laws. Most have some variations. Most States now require both parties sign a release for escrow funds. If a disagreement occurs, both parties have to fight it out in either court or decisions can be made by the state's real estate commission but most defer to the courts. In most cases of disagreement, if the holder of the escrow is a real estate brokerage, they must turn it over to the state for disposition and the brokerage is them out of the loop. If a Title Company or Attorney is holding the Escrow, a different set of state specific laws apply.

Best if the wording is included in the contract and get signatures of release.

It will also generally depend on what party caused the deal to not close.