Break up the problem,
First problem is you need to match vectors, second problem is you need to match position, third problem is how much time is available in the scenario, and forth, how much fuel the rescue vehicle has available (is there fuel aboard the derelict?) The third and fourth items become moot and uninteresting with a reactionless drive, you just use a least time course everwhere.
Needs 10 g hours to match vector in this scenario, that could be 2 hours for a 5g rescue craft, at which time the other ship gained another 10 units in distance to go with the (1+3+5+7+9)=25 that she already had.
Next you need to cover 35 units of distance in a time dictated by the avaliable fuel (if not using reactionless drives) the close the distance could take 26 hours if only 2 g hours are used 13 1/2 hours if 4 g hours are used and so on till you get to the least time/most fuel of constant acceleration with a turn over at the middle, or 5 hours at 5 g's.
So a 5 g craft could effect rescue in 7 hours starting from the location the derelict started from , needing 45 g hours of fuel to come to a stop relative to the craft's base some 35+ (10*the number of hours the rescue procedures take.) distance units away. Any fuel remaining at this point can be used to return to base, the more fuel left, the quicker the return may be made.
If the intent is to rescue the ship and tow it back, that's a different problem.
