Can a father and mother with AB blood types produce a child with type O?

Not under normal conditions.  Each person has two alleles for blood type, either of which can be A, B, or O.  In order for a person to have type-O blood, both alleles have to be O (since the O allele is recessive).  The only way a person could have AB blood is to have one A allele and one B allele.  It's 50/50 as to which allele gets passed on to the offspring; in other words, a parent with type-AB blood could pass on an A allele or a B allele, but there's zero probability of a parent with type-AB blood passing on an O allele.  In fact, if EITHER parent has type AB blood, a child of the parents cannot have type-O blood.

I hope that helps.  Good luck!

Absolutely!