Toddler being trouble with sleeping. HELP?!

So my daughter is 19 months (years and a half) blah blah. She knows how to open doors now and we have her sleeping in a toddler bed. She goes down with no problem for a nap but when it’s time for bed she’ll immediately cry, climb out of bed, and open the door and come out. Her bed time is between 9-10pm.

What can I do to keep her from opening the door and continuously come out ??