Complex sentence: Her grandson, the Tianqi Emperor, promoted her to Empress Dowager, and she was exhumed from an Imperial Concubine's tomb and re-buried in the Wanli Emperor's tomb.
Split into simpler sentences: Her grandson, the Tianqi Emperor, promoted her to Empress Dowager. Thus she was re-buried from an Imperial Concubine's tomb to the Wanli Emperor's tomb.