The ornamental design for a retaining wallblock and cap module, as shown and described.
FIG. 1 shows a perspective view of a retaining wall block and cap module;
FIG. 2 shows a front view of the retaining wall block and cap module illustrated in FIG. 1;
FIG. 3 shows a back view of the retaining wall block and cap module illustrated in FIG. 1;
FIG. 4 shows a right side view of the retaining wall block and cap module illustrated in FIG. 1;
FIG. 5 shows a left side view of the retaining wall block and cap module illustrated in FIG. 1;
FIG. 6 shows a top view of the retaining wall block and cap module illustrated in FIG. 1; and,
FIG. 7 shows a bottom view of the retaining wall block and cap module illustrated in FIG. 1.
The broken lines in the drawing views are included for the purpose of illustrating portions of the retaining wall block and cap module that form no part of the claimed design.