On the east side of San Jose, Calif., there is an abuela who seems to have more grandchildren than she can count.

“A lot of people see me and they hug me,” Mardonia Galeana, 89, said in Spanish. “I don’t even know them, but sometimes they ask me for a blessing on the street and I do the best I can on their forehead.”

Her likeness has been featured in a painting in the San José Museum of Art and in a mural in the city’s mission district. But it’s her online presence that has captivated the thousands of people who have come across the photos and videos posted by her grandson Yosimar Reyes.

“Seeing your Abuela smiling and having a good time truly warms my heart,” one user commented beneath a video of Ms. Galeana enjoying herself at a senior center while others danced to a track by the merengue singer Elvis Crespo.

Mr. Reyes has been chronicling moments in his grandmother’s life on a private Instagram account followed by more than 21,000 people. His posts have shown a trip they took to New Orleans, their strolls with his dog, Chulito, around the San Jose Flea Market, and occasional doctor visits.