答案：C.
解释：此题考查虚拟语气.
1. 固定句型It is necessary that..., It is suggested that...和It is an order that...的that从句中,都要that从句使用虚拟语气,其变化规律为：that从句的谓语动词由“should + 动词原形”构成,且should可以省略.
所以如果答案是ABD的话,则后面的that从句必须改成：
that we (should) make contact with the company.
由此排除ABD.
2. 固定句型It is time that...中的that从句也必须使用虚拟语气.
其构成是：that从句的谓语由“should + 动词原形”构成,此时should不能省略；
或that从句使用一般过去时,即其谓语动词改成过去式（如果是be动词,则一律改成were）.
而题中的从句that we made contact with the company刚好使用了一般过去时,所以答案C为正解,当然也可以写成that we should make contact with the company.