I think the reason Amma asked her to leave was bcos she herself made the decision to stay in D house until Mandar was ok, and she dint consult Raghav or Amma regarding this. So for the time being, D house is her house and thats where she is staying. If she would have told Amma that she left that house and has come back to her house, Amma would have let her in.
And when Raghav is drunk, he behaves really hurtful, so Amma must have thought its better Pallu doesnt come in front of him, or else his entire anger would be directed towards her and he would have behaved badly with her. So to protect Pallu from Raghav's wrath, and to not have further drama and show downs in her house, she must have asked her to leave.
As far as Keerti closing the door is concerned, I dont think Amma is responsible for it as Keerti just did it quickly bfor Amma could react or ask her not to. Anyways, Amma knows that nowadays Keerti doesnt really listen to her, be it in case of Sunny or when it comes to behaving properly with Pallu.