Before festivals the shops are thronged with men, women and children making various purchase.

Men, women and children throng the shops before festival making various purchases

The shops are thronged by people making purchases

During festival people throng the shops

Men, women and children make purchases during festivals

All of the above

Given sentence is in Passive voice and in Present Simple Tense.

We need to change it into active voice.

While changing the voice objects becomes subject and subject changes into object.

Rule :

Subject + V1 + Other agents.