at my mother's (?)

[Liza]

Hi,

I always have problems how to say the following sentence correctly.

Last weekend I was at my mother. (?)
Last weekend I was at my mother's. (?)
Last weekend I was at my mother's house. (?)
Last weekend I was at my mother's home / flay. (?)

(I want to say that I visited my mother.)

Thankx
Liza

[Mrv]

i generally say:
I visited my mother last weekend
or
I visited my mom last week and i worked on the house - mostly painting the house.