noun

the state or feeling of being calm and in control of oneself.

she was struggling to regain her composure

self-control,self-possession,self-command,calmness,equanimity,equilibrium,calm,coolness,collectedness,serenity,tranquillity,aplomb,poise,presence of mind,sangfroid,self-assurance,assurance,imperturbability,placidity,placidness,impassiveness,impassivity,dispassion,phlegm,stolidity,unexcitability,cool,unflappability,countenance,ataraxy,ataraxia