The One Where Nana Dies Twice - S1-E8
Other mistake: When Ross is helping choose a dress and shoes for Nana to wear, he is behind the chest of drawers in the cupboard. He looks in a shoebox and finds lots of pink sweet'n low packets, then pulls down another box and lots of packets fall down on him. However, it is obvious that someone is above him showering the packets down, as they are coming from directly above him, not from on top of the door. (00:12:35)
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.