My mother In-law wan't to gift us $57,600 towards a new home. Will we have to pay taxes on the gifted money?

Gifts received from an individual are not reported on a tax return, regardless of the amount received.

You may have heard of the "gift tax".  The gift tax return is filed by the person giving the gift, not the one receiving it. "Gift Tax" is somewhat of a misnomer.  Even though a gift tax return may be required, very few people ever actually pay federal gift tax. The purpose of the gift tax return is usually only to document a reduction in the allowable estate tax exemption.
See <a rel="nofollow" target="_blank" href="https://turbotax.intuit.com/tax-tools/tax-tips/Tax-Planning-and-Checklists/The-Gift-Tax-Made-Simple/INF12127.html">https://turbotax.intuit.com/tax-tools/tax-tips/Tax-Planning-and-Checklists/The-Gift-Tax-Made-Simple/INF12127.html</a>