I kept the little girl ______ till her parents returned home.

选C。Keep sb. company 陪伴某人。固定搭配

company的中文翻译
以下结果由译典通提供词典解释
名词 n.

1.公司,商号[C][G]
Tom works for a computer company.
汤姆在一家电脑公司上班。
2.剧团[C][G]
3.陪伴;友情[U]
4.伴侣(们);同伴(们),朋友(们)[C][G]
People are judged by the company they keep.
根据某人结交的朋友便能判断其人了。
5.客人(们)[U]
Do you expect company for the weekend?
这个周末你家有客人吗?
6.【军】连[C][G]
7.全体船员(包括船长等)[C][G]

companion的中文翻译
以下结果由译典通提供词典解释
名词 n. [C]

1.同伴,伴侣;朋友
Are you alone or with a companion?
你单独一人还是与朋友在一起?
2.(受雇服侍老人或病人的)看护妇
3.成对(或成副等)的物件之一[(+to)]
4.(常用作书名)指南,手册[(+to)]
The Gardener's Companion was written by David Green.
《园艺指南》是戴维·格林写的。
5.【天】伴星

及物动词 vt.

1.陪伴

选D

to keep someone company 陪伴某人 是固定词组

所以选C