Yo soy la mamá y tengo 50 años. Mi tiene 12 años. Él es creativo.
1) padre
2) madre
3) hermana
4) hijo

Hijo

Explanation:

You can tell the mom is talking about a male because she is speaking in masculine that leaves only as possible answers:

- padre - hijo

The translation is:

I'm a mom and I'm 50 years old. My is 12 years old. He is creative.

So, it's clear that she is talking about her son once you translate it.

Hope it was helpful ;)