How to make an emergency milk bottle?

Use a medicine dropper.
Dribble milk into the side of the baby's mouth. Allow time for swallowing before inserting the next dropper-ful.

Use a straw.
Suck fluid into a straw and sustain tension by placing your thumb on the top of the straw. Put the straw into the side of the baby's mouth and remove your thumb periodically from the straw, releasing the tension and allowing the liquid to dribble out at intervals.