Here's why it's a difficult question:
* The charm was meant to protect Harry from Voldemort. It's clear that Lily's sacrifice was specifically aimed at shielding Harry from Voldemort's killing curse. It's never stated or implied that it would extend to protecting him from any and all harm.
* Dobby's attack was not a direct attack on Harry. Dobby didn't intend to kill Harry, just to prevent him from going back to the Dursleys. Dobby's magic was fuelled by his loyalty to Harry, not by malice.
* The charm's potency is unclear. We know the charm had a strong effect on Voldemort, but the limits of its power remain undefined. Could it shield Harry from all harm? Could it protect anyone else? These questions are unanswered.
Possible outcomes:
* The charm could have protected Lucius. It's possible that the charm would have extended its protection to any attack on Harry, even if it wasn't a direct attempt to kill him. In this case, the charm could have neutralized Dobby's spell or weakened it significantly.
* The charm could have been ineffective. It's also possible that the charm only protected against Voldemort's magic or against specific types of harm. Dobby's attack might not have fallen under its purview.
* The charm could have interfered with Dobby's magic. It's conceivable that the charm could have reacted with Dobby's magic, creating unpredictable results. Perhaps the charm could have deflected the attack, or maybe it could have intensified it.
Ultimately, the answer to this question is left to interpretation and speculation. J.K. Rowling has not explicitly defined the exact parameters of Lily's love charm, leaving room for various possibilities.