Check Lazada see whether got sell or not. Last time I saw but it is aradio with cassette, larger and not really convenient to carry around.
Otherwise, you can try to convert all the cassette into MP3, buy a speaker with USB and play it from SD card or pen drive. I believe those larger sd card or pen drive can even fit all the songs in.
No wire involve apart from maybe charging the speaker.
It really takes time, you just be patient and teach her all the way and it will be good.