7 mothers.

 …According to scriptures also, there are seven mothers: (1) the real mother, (2) the wife of the spiritual master, (3) the wife of a brāhmaṇa, (4) the wife of the king, (5) the cow, (6) the nurse, and (7) the earth. All of them are mothers.

Srimad Bhagavatam
By His Divine Grace A.C. Bhaktivedanta Swaim Prabhupada
from Canto 1, Chapter 11, Text 28-

Seven Mothers

praviṣṭas tu gṛhaṁ pitroḥ
pariṣvaktaḥ sva-mātṛbhiḥ
vavande śirasā sapta
devakī-pramukhā mudā

praviṣṭaḥ—after entering; tu—but; gṛham—houses; pitroḥ—of the father; pariṣvaktaḥ—embraced; sva-mātṛbhiḥ—by His own mothers; vavande—offered obeisances; śirasā—His head; sapta—seven; devakī—Devakī; pramukhā—headed by; mudā—gladly.

After entering the house of His father, He was embraced by the mothers present, and the Lord offered His obeisances unto them by placing His head at their feet. The mothers were headed by Devakī [His real mother].

It appears that Vasudeva, the father of Lord Kṛṣṇa, had completely separate residential quarters where he lived with his eighteen wives, out of whom Śrīmatī Devakī is the real mother of Lord Kṛṣṇa. But in spite of this, all other stepmothers were equally affectionate to Him, as will be evident from the following verse. Lord Kṛṣṇa also did not distinguish His real mother from His stepmothers, and He equally offered His obeisances unto all the wives of Vasudeva present on the occasion. According to scriptures also, there are seven mothers: (1) the real mother, (2) the wife of the spiritual master, (3) the wife of a brāhmaṇa, (4) the wife of the king, (5) the cow, (6) the nurse, and (7) the earth. All of them are mothers. Even by this injunction of the śāstras, the stepmother, who is the wife of the father, is also as good as the mother because the father is also one of the spiritual masters. Lord Kṛṣṇa, the Lord of the universe, plays the part of an ideal son just to teach others how to treat their stepmothers.

Source : https://theharekrishnamovement.org/tag/mothers-day/