/home/user/foo/
  a_1.0
  a_1.1
  b_1.0
  b_1.1
  c_1.0
  c_1.1

/home/user/foo/
  a_1.1
  b_1.1
  c_1.1

#!/bin/bash
find . -name "a_*" -print0 | xargs -r -0 ls -t | head -1
find . -name "b_*" -print0 | xargs -r -0 ls -t | head -1
find . -name "c_*" -print0 | xargs -r -0 ls -t | head -1