I assume you're asking about her nationality, not the ethnicity, because the latter cannot be derived in any way other than guessing from the place of birth. Now, for the purpose of this entry let us define the 'interwar period' as 11/11/1918 - 31/8/1939. Between 1812 and 1918 Chisiniau (Chisinau, Kishinyev) along with the entire Moldovan region belonged to Russia. On 2nd December 1917 (all dates according to Eastern calendar), State Council proclaimed the Moldavian Democratic Republic encompassing Bessarabia with Chisiniau and supporting the Temporary Government in Russia. Council then asked the Romanian government for help against local bolsheviks and Ukrainians who also claimed the right to this land, what prompted immediate intervention of the Romanian army. On 14th January 1918, bolsheviks conducted a coup d'etat that forced pro-Romanian Council to suspend their actions, but then they were driven out by the Romanian army. With the strong pressure from the Romanians, Council declared complete independence of the Moldavian Republic and on 27th March 1918 voted for union with Romania, although with strong military pressure from the latter country. Due to decisive political actions from the pro-Romanian Moldavian Bloc headed by Pantelimon Halippa, the Moldovan plans for autonomy did not fall through and on 27th December 1918 Moldavian Republic was de facto incorporated into Romania. It is important not to mistake Moldovan Democratic Republic with the Moldavian Autonomous Soviet Socialist Republic proclaimed in 1924 and formed of the territory of Transnistria inhabited mostly by ethnic Ukrainians (with its border on the Dniestr river being located less than 20 km east from Chisinau).

So, from the political perspective, anyone born in Chisinau of the local parents (as opposed to children of foreigners who happened to reside in the city at the time) after the 27th December 1918 and before the annexation by USSR in 1940 were subjects to the Romanian king i.e. were Romanians. Those born between the end of Great war and incorporation of the autonomous Moldovan Republic into Romania could be said to be citizens of Moldavia i.e. Moldavians.