You typically need to place two bombs to kill them. Place the second shortly after the first and it will kill the Beetom on your way down. Killing one Beetom is all that is needed to get to the farm.

Requires:

{
  "enemyKill": {
    "enemies": [
      [
        "Beetom"
      ]
    ],
    "explicitWeapons": [
      "Bombs"
    ]
  }
}
{
  "enemyDamage": {
    "enemy": "Beetom",
    "type": "contact",
    "hits": 2
  }
}

Clears obstacles: A