Grusha confirms that she is motherly enough hence deserves baby Michael through the various sacrifices and suffering she undergoes in order to protect and eventually adopt the child.
For instance, she risks her life and that of the child by crossing a rotten bridge at the verge of collapsing which exposes them to danger.
She spends her entire weeks savings to buy a pitcher of milk for the baby ie financial sacrifice.
She hits a corporal on the head in a move to protect baby Micheal from the Ironshirts pursuing him at the order of Fat Princes.
She accepts to marry Jussup with a view to protecting Michael and finding a farm for them to stay after Aniko complains about their prolonged stay in her house. Grusha sacrifices her commitment to Simon as a result.