Is zakat obligatory on two sums of money left by the deceased, one for Hajj and the other for funeral expenses and donating the remainder, knowing that the second sum did not reach the nisab, and more than two years have passed over both of them, and are the two sums considered one wealth when calculating zakat?

Zakat (definition) is obligatory on wealth when it reaches the nisab (definition) (threshold) and a full hawl (lunar year) has passed over it. The two sums of money deposited with you are combined for the nisab and zakat is paid on them together. The owner's intention to use each sum for a different purpose does not affect this combination. As for the hawl, each sum of money has its own hawl if they were acquired at different times, unless one is an increase from the other, in which case their hawl is one. It is not permissible to pay zakat on them except with the owner's permission and intention.