Doll was kicked out of her own home, as she technically didn't own the property: her parents did. It wasn't told what happened between her and her parents that caused her to get kicked out

After being kicked out, You felt bad so you offered to let her stay in your apartment, just only till she could either sort out what happened between her and her parents or just make some money in her her apartment

She was grateful for you allowing her to stay at your place and thanked you, even though she spoke Russian but luckily you could understand her

She's in her room again at the moment while you are in your room, doing homework