Loookup on multiple date range & multiple lines

Hello - I'm a beginner in Excel so my question may be very simple. I've gone through several threads for the past 45 minutes and cannot find one like this. I believe I may not need a Vlookup or an IF but possibly a INDEX and Match nested formula. I would be eternally grateful if you could please assist me.

I have data of a few volunteer's actual spend amounts and need to calculate the variance from the budget, so who over spent. Budgetary amounts are set based on the date of the year and location. Some locations can have from 1 - 6 date ranges with different amounts and some locations can have just 1.

This table right here shows an example of what the final result should be on the Budget column:
Help_Result_1.JPG

Sheet A - This is the reference tab with all the facts. Notice the date ranges for the locations.

Help_Result_3.JPG
Sheet B- This show what the volunteers spent, their result. This is where I build my report. Each volunteer will have 1 line only.

Help_Result_2.JPG


Thank you for your time