There are sing alongs almost very day at OS Cafe on 6th Ave between 14th and 15th sts. I'm not sure exactly what the schedule is, but she can call or stop by to find out. We often go to the Friday 11am sing along with Amy, who is great.
Also, the playground on 6th and 18th st has water play areas and good shade, a good outdoor option on hot days though it gets busier in the afternoons when the bigger kids get out of the school next door.
The library on 9th St and 6th ave has story times on Mondays and Tuesdays though their schedule and hours are changing now for summer, so best to call to find out what they'll have going on next week.
Finally, Juguemos a Cantar on 6th ave btw 10th and 11th has had morning play space hours most days, though this week or next is the last week before they switch to summer hours. again, best to check their website or call to check the schedule.