Mark 16 Commentary Series: Verse 12

After that he appeared in another form unto two of them,

as they walked, and went into the country.

Mark 16:12

Adam Clarke
Charles Spurgeon
Matthew Henry

These were the two who were going to Emmaus. The whole account is given by Luke, 24:13-34.
This refers, no doubt, to that which is largely related (Luke 24:13, &c.), of which passed between Christ and the two disciples going to Emmaus.