Solutions :

3-letter words (1 point): 27

EMS; EMU; ENS; ESS; INS; ISM; MEN; MES; MEU; MIS; MUS; NIM; NIS; NIT; SEX; SIM; SIN; SIT; SUE; SUM; TIN; TIS; TIT; UMM; USE; VEX; VUM.

4-letter words (1 point): 26

EMIT; EMUS; ESNE; EXES; ISMS; MESS; MEUS; MINT; MINX; MISE; MITT; MUSE; NEMN; NEUM; NIMS; SEMI; SESS; SIMS; SMIT; SNIT; SUES; SUMS; TIME; TINS; TINT; USES.

5-letter words (2 points): 9

MENSE; MESNE; MISES; MUSES; MUSIT; NEMNS; SEMIS; TIMES; VEXES.

6-letter words (3 points): 4

MENSES; MINXES; TINMEN; TITMEN.

7-letter word (7 points): 1

IMMENSE.