I just lost my grandmother. She raised her 5 children alone. I am looking for things in the Tanakh or Talmud to cheer my dad up. Is there anything in the Tanakh or Talmud about a woman that raises her children alone?
Chiram, the craftsman who designed much of the first Beis Hamikdash, was the son of a widow (1 Melachim 7:14).
The woman from Tzorfas who hosted Eliyahu was a widow with a son (1 Melachim 17:9-24), and there's a Midrash (don't remember the location) that he grew up to be the prophet Yona
Also the "wife of one of the disciples of the prophets" (2 Melachim 4:1) was a widow with children whom she raised.
Reish Lakish's wife raised their son after he passed away, and this son was able to tell R' Yochanan a new explanation of a posuk (Taanis 9a).
It may be worth investigating Tzipora, the wife of Moshe Rabbeinu. She raised their sons without him between the time that he returned to Egypt at God's command and when Yitro brought her and the boys to join the Israelites in the desert (Exodus 18:1-4), which was either after the Exodus or after the Assembly at Sinai when the Torah was given. So, she definitely single-parented for a while, there.
Her agency was highlighted right before that separation period, when she circumcised her son (Exodus 4:24-26), presumably having to do so because Moshe had not done it himself, for whatever reason.
Finally, according to Rashi's comment on Numbers 12:1, Moshe separated from Tzipora essentially permanently, so that he could be constantly ready to receive prophecy. This refers, I believe, specifically to abstaining from sexual relations, but one might speculate that similarly, Moshe's duties as prophet for the ages, teacher of a nation, chief justice, and leader also kept him away from other family involvement, including child-rearing.
I understand by raising children you mean to teach them mitzvot
Yes there is in the Talmud a queen ( Queen Helena in Lydda) that taught (rose) her sons to sit in a suka
If you will answer [with regard to her seven sons] that her sons were minors and minors are free from [the obligation of] the sukkah, since [however] she had seven, there must have been at least one who was [old enough] not to be dependent on his mother; and if you will object that [the duty of educating] a child who is not dependent on his mother is merely a Rabbinical injunction, and she took no heed of a Rabbinical injunction,
- Hagar raised Yishma'el alone after the two were exiled from Abrtaham's house
(You didn't indicate that you were seeking only "Jewish" sources).
- Naomi raised Machlon and Kilion after Elimelech died
Chana and her seven sons in the Chanuka story