My mother-in-law wants to add my husband on to deed (not sure as beneficiary or co-owners). Her name is only on the mortgage.

My mother-in-law wants to add my husband to her deed( not sure as beneficiary or co-owners). Her name is only on the mortgage. Would we be responsible for mortgage payments? And is there any chance if someone say fell on the property we could get sued? What would be the best thing for us?