json decode yerine json_encode yapın hocam
"{\"dynamic_form[dynamic_form][0][p_name]\":\"Soru Ad\u0131\",\"dynamic_form[dynamic_form][0][c1]\":\"\u015e\u0131k1\",\"dynamic_form[dynamic_form][0][c2]\":\"\u015e\u0131k2\",\"dynamic_form[dynamic_form][0][c3]\":\"\u015e\u0131k3\",\"dynamic_form[dynamic_form][0][c4]\":\"\u015e\u0131k4\",\"dynamic_form[dynamic_form][0][dogru]\":\"D\\tCevap (1-4 aras\u0131 bir say\u0131 yaz\u0131n.)\",\"dynamic_form[dynamic_form][1][p_name]\":\"Soru Ad\u0131\",\"dynamic_form[dynamic_form][1][c1]\":\"\u015e\u0131k1\",\"dynamic_form[dynamic_form][1][c2]\":\"\u015e\u0131k2\",\"dynamic_form[dynamic_form][1][c3]\":\"\u015e\u0131k3\",\"dynamic_form[dynamic_form][1][c4]\":\"\u015e\u0131k4\",\"dynamic_form[dynamic_form][1][dogru]\":\"Do\u011fru Cevap\"}"Bu şekilde çıktı alıyorum.