The ornamental design for a markerholder and eraser, as shown and described.
FIG. 1 is a left side perspective view of a marker holder and eraser showing our new design;
FIG. 2 is a top view of the marker holder and eraser shown in FIG. 1;
FIG. 3 is a bottom view of the marker holder and eraser shown in FIG. 1;
FIG. 4 is a right side view of the marker holder and eraser shown in FIG. 1, the left side view being a mirror image thereof;
FIG. 5 is a front side view of the marker holder and eraser shown in FIG. 1; and,
FIG. 6 is a back side view of the marker holder and eraser shown in FIG. 1.
The broken lines showing portions of the design in FIGS. 1, 2, and 5 are included for the purpose of showing features that form no part of the claimed design.