The description of on xrpl.org of EscrowFinish fees/costs assumes a 10 drop ledger base fee. However, many validators are voting for 200 drops, so this value may change in the future.
Here's a helpful link for how rippled computes the EscrowFinish fee (at least, for escrows that have Fulfillments): https://github.com/XRPLF/rippled/blob/master/src/xrpld/app/tx/detail/Escrow.cpp#L368