Insurance fraud is a felony. But say the DA won't prosecute. If the insurance company does not pick up the lie, and there is no physical or the paramedical person or doctor also misses it, and the company winds up issuing the policy, and your father dies within 2 years, the insurance company treats the claim as "contestable" and will not pay until after it has concluded an investigation. And you had better believe the company will find out the facts in a case like this. And the company will not pay. (And that's often when the companies call the prosecutors.)

What if your father dies after 2 years from policy issue, and the company has not caught on before then? (It has to act to "rescind" within the 2 years.) Then that's a different story. In some states, even with the actual fraud, your mom may collect; in others if there is real fraud, perhaps not. (BUT your mother then may be the subject of criminal charges, as the statute of limitations is usually far longer than 2 years.)

I strongly recommend not lying. Life is too short. And the possible money you may make by cheating an insurance company -- even if you can get away with it -- is rarely worth the shame and guilt that can result.