I dont run Pi-hole on Xbian anymore but seems your assumption is correct about returning only a single line:
xbian@avr ~ $ ldd /bin/ls | grep -E '^\s*/lib' | awk '{ print $1 }'
/lib/libarmmem.so
/lib/ld-linux-armhf.so.3
Also does below symlink exist on your XBian version ?
xbian@avr ~ $ readlink -f /lib/ld-linux-armhf.so.3
/lib/arm-linux-gnueabihf/ld-2.28.so
xbian@avr ~ $ dpkg -S /lib/arm-linux-gnueabihf/ld-2.28.so
libc6:armhf: /lib/arm-linux-gnueabihf/ld-2.28.so
Latest Xbian does have but older versions needed to symlink:
I believe this to be apache2 related like wrong config and/or PHP mods missing.
Search discourse here for apache2 related threads.
EDIT: Ps. you can default the web files with below if necessary: