What happens when the executor dies before the distribution to the beneficiary and the beneficiary dies and has no heirs?

You need to speak with the attorney who is handling the estate. There are many variables in your situation that must be reviewed by an attorney.

The court would need to appoint a new executor. The timing of the death of the beneficiary would dictate where the property will go. If the named beneficiary died prior to the testator then the property will remain in the testator's estate and be distributed as intestate property to the heirs-at-law of the testator. If the beneficary died after the testator died then the property is in the beneficiary's estate. That estate would need to be probated and any intestate property would 'escheat' to the state if there are no heirs-at-law. If the beneficiary has a will, the property would pass according to the will once it has been probated.

You can check the laws of intestacy for your state at the related question link provided below.