The four cells in this question have already gone through meiosis I and are now going through meiosis II. Since there are four cells after meiosis I, this means there were two cells prior to meiosis I. When these four cells go through meiosis II, eight cells are produced.
Prior to meiosis: Two diploid cells with seven pairs of homologous chromosomes
After meiosis I: Four haploid cells each with seven chromosomes with duplicates
After meiosis II: Eight haploid cells with seven chromosomes in each, but the chromosomes are not duplicated.