We derive a boundary condition for the Nambu Keldysh Green's function in diffusive normal metal-unconventional superconductor junctions applicable for mixed parity pairing. Applying this theory to a 1d model of s+p-wave superconductor, we calculate LDOS in DN and charge conductance of DN-s+p-wave superconductor junctions. When the s-wave component of the pair potential is dominant, LDOS has a gap like structure at zero energy and the dominant pairing in DN is even-frequency spin-singlet s-wave. On the other hand, when the p-wave component is dominant, the resulting LDOS has a zero energy peak and the dominant pairing in DN is odd-frequency spin-triplet s-wave. We show the robustness of the quantization of the conductance when the magnitude of p-wave component of the pair potential is larger than that of s-wave one. These results show the robustness of the anomalous proximity effect specific to spin-triplet superconductor junctions.