Please note that both MHS and NHS are national clubs that most of students can join at ease. I believe the only “toughest” requirement for joining MHS is taking Precalc in the current year and that for joining NHS is having 3.5 GPA or some sort. Just writing down that you are part of those two just amounts to “bragging” that you are currently in precalc and have a GPA higher than 3.5, both of which are not impressive at all and are shown on high school transcripts anyway.
Also, as far as I know, your community service history is shown on service transcript if you are worried about your cumulative service hour log. Honestly, if you are really still paranoid, then think back on how many hours you earned from MHS and NHS. If you have not earned much hours from them, then telling them that you were part of NHS and MHS may rather work against you as you didn’t perform well during your time as a member.