Quantum many-body scars enable long-lived coherent dynamics in otherwise thermalizing systems, but controlling their stability under periodic driving remains challenging. We study the PXP model subjected to a continuous two-frequency drive and show that the frequency ratio $c={\omega }_2/{\omega }_1$ acts as a control parameter for the resulting Floquet dynamics. In a rotating-frame description, the drive generates Bessel-dressed couplings in an effective Floquet Hamiltonian whose harmonic content depends explicitly on $c$. This $c$-dependent dressing changes the competition between coherent revival dynamics and thermalization. Small integer values of $c$ stabilize scar-induced oscillations down to substantially lower driving frequencies than in the single-frequency limit. At fixed low frequency, small noninteger rational values of $c$ can instead produce isolated suppressions of coherent revivals, an effect that weakens as $c$ increases. Successive Fibonacci rational approximants also reproduce the quasiperiodic dynamics over finite observation times. We further show that two-frequency driving produces tunable rational subharmonic responses in local observables, including higher-order responses that are relatively stable for small $c$ compared with those in the corresponding single-frequency protocol. Our results demonstrate that two-frequency driving provides a route to controlling prethermal nonergodic dynamics and temporal responses in the constrained PXP model.