قَامَتِ الْمَرْأَتَانِ كِلْتَاهُمَا — Both women stood.
قَامَتْ: past verb with feminine tāʾ; the connecting kasrah on t is phonetic.
الْمَرْأَتَانِ: nominative feminine dual subject marked by alif.
كِلْتَاهُمَا: nominative semantic emphasis by alif, with humā as mudāf ilayh.
Use kiltā for the feminine dual, not for any arbitrary feminine singular.