It could if the speaker is referring to a different mother than his/her own, as we generally use "Mother" to refer to ourbown mom. But in that case, I think I would use a demonstrative or personal pronoun like "that mother" or "their mother", or something similar. As an English speaker, that is.
It would be äiti maalasi talon if it were completed. Äiti maalaa talon would probably be used to describe an assigned task, a regular practice, something that mother generally does but is not doing right now. With some further contextual reference to a future event, it could also be "mother will paint the house".