Will Allah take this girl's right from the mother? And will that be through the questioner and her sister?

If a mother harms her daughter through backbiting or mockery, she is an oppressor, and she must repent sincerely, for the consequences of oppression are dire. The basic principle is that a Muslim is not held accountable for the misdeeds of another, as Allah Almighty said: "And every soul earns not [anything] except for itself, and no bearer of burdens will bear the burden of another. Then to your Lord is your return, and He will inform you about that over which you used to differ." Therefore, it is not necessary that you be afflicted with harm because of your mother's oppression, and the suitors' turning away might just be a trial. One must beware of obsessive thoughts and proceed with marriage due to the good and benefits it contains, both in this world and the hereafter.