Particle-stabilized emulsions (Pickering emulsions) have gained significant interest due to their high stability, tunability, and biocompatibility. This study presents the synthesis of colloidally stable nanoparticles and the formation of stable Pickering emulsions using pH and electrolyte-responsive silica nanoparticles functionalized with a mix of silanes containing amine/ammonium groups. Colloidal stability of the silica nanoparticles is enhanced when functionalized with a mixture of silanes compared to single-silane functionalization. Nanoparticle suspensions synthesized with a 50:50 mixture of N1-(3-trimethoxysilylpropyl) diethylenetriamine and N-trimethoxysilylpropyl-N,N,N-trimethylammonium in complex brine containing various salts remain suspended under 500xg acceleration and temperatures up to 60 °C. In contrast, single-silane functionalized particles show far less stability. This improved stability is linked to the silane-grafted layers and surface roughness, as observed via Atomic Force Microscopy (AFM). The assembly of nanoparticles at the oil-water interface is influenced by electrostatic interactions between the particles and oil, and interparticle interactions, modulated by pH or salt addition. Under acidic conditions, with positively charged oil-water interfaces and nanoparticles, no significant reduction in interfacial tension is observed. Conversely, under basic conditions where the oil-water interface is highly negatively charged and the amine groups on the silica particles are deprotonated, the nanoparticles assemble densely at the interface, resulting in a high dilatational modulus. This prevents oil droplets from coalescing, significantly enhancing emulsion stability. When suspended in brine containing 56,000 g/L of monovalent and divalent salts, nanoparticle assembly at the oil-water interface is more pronounced compared to DI water at pH 7. Ultra-small/small-angle X-ray scattering measurements confirm nanoparticle assembly at the interface, with time-dependent scattering measurements revealing a two-step assembly process consistent with interfacial tension dynamics. The assembled nanoparticles at the interface induce a solid-like behavior or jamming, making the interface act like an elastic membrane with high dilatational and storage moduli.This study provides fundamental insights into the surface and interfacial properties of silane-grafted nanoparticles, highlighting ways to optimize their assembly at oil-water interfaces while enhancing their colloidal stability under harsh conditions. These findings have implications for environmental remediation, catalysis, drug delivery, food technology, and oil recovery applications.