Learn Spanish (Latin America): La casa es de la familia.

In Spanish, possession is usually expressed using the verb ser (to be) followed by de (of). So, es de la familia literally translates to 'is of the family', which is the natural way Spanish speakers say 'belongs to the family'.

Could we use the plural verb 'son' since a family has multiple people?

No, because the verb must match the subject of the sentence, which is La casa (The house). Since there is only one house, we use the singular es (is). If we were talking about multiple houses, we would use the plural: Las casas son de la familia.

Is there a way to use an apostrophe 's' in Spanish to say 'the family's house'?

Spanish does not use an apostrophe 's' to show ownership. You must always use the word de (of) to show who owns what. If you wanted to say 'It is the family's house', you would phrase it as 'It is the house of the family' (Es la casa de la familia).