My first language is English, but I've been learning Ukrainian for the last year. While everyone on this sub can tell you that my Ukrainian is far from perfect, it might really help you to learn some key phrases that address the most basic needs.

Ви треба допомагає? Pronounced "Vі - treba - do-po-ma-hi-yay" - Do you need help?

"Ви холодно?" pronounced "Vi ho-lohd-no" - are you hungry?

"Ви треба лікар" - pronounced "Vi - treba - leekar" - Do you need a doctor?

"Я хочу допомагати" - pronounced "Ya - hochu - doh-poh-ma-hа-tee" - I want to help.

"Cкажіть мені що ви треба" - ska-jeet meh-ni sch-cho vi treba" - tell me what you need.

I am sure that these are not grammatically awesome, but they can at least establish whether there is some emergency or need that must be met. OP, I would suggest that, at the very least, you learn to read Cyrilic (the alphabet is very similar to ours and only takes a couple days). You don't need to be fluent in Ukrainian to make sure that your guest is okay!