If you can pay the bill without expecting to be paid back then go for it...if you would need paid back you should wait to hear from her.
I just paid my daughters power bill with knowing I won't be paid back. She doesn't know why they didn't cut her off but she finally called and was told the bill had been paid. She thinks one of the local agencies paid it for her. That's ok because I have the peace of mind of knowing my grandson won't lose his computer!