Rumer Willis At Demi Moore's House During 911 Emergency

Rumer Willis was at her mom's home when Demi Moore went into a semi-conscious, convulsive state.

If you listen to the 911 tape -- around the 00:54 mark -- you'll hear the caller ask, "What is the address Ru?"

What's interesting ... Demi was clearly smoking something and, we're told, inhaling nitrous oxide with her daughter right there.